Augmented Reality vs Virtual Reality

1.1 What is augmented reality?

Augmented reality (AR) adds digital content to what you already see. IBM describes it as digital information added to a user’s surroundings in real time. It overlays content onto the real world. It enriches what a user perceives. It does not replace reality.

Users still see and interact with their physical surroundings. IBM says AR overlays content onto the real world.

AR devices carry cameras, sensors and displays. IBM lists smartphones and tablets. It also lists wearables such as smart glasses and headsets.

Here is a familiar picture. Imagine your phone camera pointed at the floor. A cartoon character stands on it. You still see the floor. That is AR. The game IBM names is Pokemon GO. It blends virtual creatures into real places. The cartoon character is a made-up example.

1.2 What is virtual reality?

Virtual reality (VR) immerses users in a digital environment. IBM says this is usually done with a VR headset or VR goggles. Unlike AR, VR completely replaces the physical world. It surrounds users with a 360-degree view of computer-generated environments.

Microsoft says the same in one line. Experiences that block your view to give a fully immersive digital experience are virtual reality. To occlude means to block.

A head-mounted display is a screen worn on the head.

1.3 How do the two compare side by side?

The table covers only AR and VR. Mixed reality is in card 5. The quick-test row is our own summary of the IBM and Microsoft lines above.

2.1 What is a see-through display?

Microsoft’s documentation describes two kinds of headset. It calls them holographic devices and immersive devices. The difference lies in the display.

The wording is Microsoft’s. Microsoft also says a device may be tethered to a PC or untethered. That does not decide its type. The table does not cover phone-based AR.

The see-through display matches the AR idea. It keeps the real world in view. The opaque display matches the VR idea. It closes the real world off. This link is our own reading; Microsoft calls these devices holographic and immersive.

2.2 Does AR need a headset?

No. IBM lists smartphones and tablets as AR devices. It adds smart glasses and headsets. The UPSC statement in card 9 names the camera of a smartphone or PC.

2.3 Does VR always hide the room completely?

Microsoft adds one detail. In virtual reality, nearby walls and furniture are shown digitally inside the experience. The user can then avoid colliding with them.

3.1 Why do students mix up AR and VR?

The two terms are easy to swap. It is easy to attach the right description to the wrong name.

UPSC used this in its 2019 question. Two statements swapped the descriptions. Two statements gave them correctly.

3.2 Which statements were right and which were wrong?

Statement wording is shortened here. The full official wording is in card 9.

3.3 Is there a quick memory aid?

Try this. AR adds to the real world. VR visits a made-up world. This is a memory aid, not a source line. It works because AR keeps you where you are. VR moves your view elsewhere.

3.4 How can you eliminate options step by step?

• Statement 1 describes VR, so any option that includes statement 1 is out.
• Statement 2 describes AR, so any option that includes statement 2 is out.
• That removes the options “1 and 2 only” and “1, 2 and 3”.
• Statement 3 is correct, so “4 only” is incomplete.
• The option “3 and 4” is left, and it matches the official key.

4.1 How does a phone know where it is?

Google’s ARCore is a toolkit for phone AR. As the phone moves, ARCore runs a process called SLAM. The full name is simultaneous localization and mapping. This helps it understand where the phone is relative to the world around it.

ARCore detects visually distinct features in the camera image. It calls them feature points. It uses these points to compute the phone’s change in location.

ARCore also combines this with inertial measurements from the device’s IMU. The IMU is a motion-sensor unit. Together they estimate the camera’s pose over time. Pose means its position and orientation.

IBM says AR software may also use data from accelerometers, gyroscopes, GPS or lasers. This comes alongside a video stream.

4.2 How does a virtual object sit on a table?

• Surfaces: ARCore identifies horizontal and vertical surfaces as geometric planes. Virtual objects can then be placed on them.
• Depth: ARCore can create depth maps that show the distance of surfaces.
• Light: ARCore provides information about environmental lighting. Virtual objects can then be lit realistically.

ARCore also warns about a limit. Flat surfaces without texture may not be detected properly. A white wall is one example.

4.3 Do all AR apps need a trigger?

IBM names two basic types of AR.

• Marker-based AR overlays digital content onto a physical trigger. The trigger might be a QR code, an image or another target marker.
• Marker-less AR needs no specific trigger. It relies on device sensors such as GPS, accelerometers and cameras to map the user’s surroundings in real time.

ARCore says the rendered virtual image can be overlaid on the camera image. That makes the content appear to be part of the real world.

5.1 What is mixed reality?

Mixed reality blends the physical and digital worlds. Microsoft says some experiences can move between augmented and virtual realities. These form mixed reality.

IBM frames it a little differently. It calls mixed reality an umbrella term for some advanced forms of AR. Digital content interacts with the real world. Virtual objects blend with the physical environment.

For the exam, keep to the two terms in the question. Use mixed reality only as background.

5.2 What is the reality spectrum?

Microsoft describes a spectrum. Physical reality sits at one end and digital reality at the other. Mixed reality covers the space between them.

• Near the physical end, users remain present in their physical reality. They are not made to believe they have left it.
• In the middle, experiences blend the real world and the digital world.
• Near the digital end, users experience a digital reality. They are unaware of the physical reality around them.

That Microsoft page does not say where AR or VR sit on the line. So do not mark them on it yourself.

5.3 Who introduced the term?

Microsoft says the term mixed reality comes from a 1994 paper. Paul Milgram and Fumio Kishino wrote it. The paper is titled “A Taxonomy of Mixed reality Visual Displays”.

A related paper has the title “Augmented reality: a class of displays on the reality-virtuality continuum”. Its authors are Milgram, Takemura, Utsumi and Kishino. Crossref lists it in SPIE Proceedings volume 2351.

6.1 Who wrote about a head-mounted display in 1968?

Ivan E. Sutherland wrote a paper titled “A head-mounted three dimensional display”. It appeared in the proceedings of the Fall Joint Computer Conference. The conference ran from 9 to 11 December 1968 in San Francisco.

The Computer History Museum says Sutherland introduced several concepts. These include 3-D computer modeling, visual simulations, computer aided design and virtual reality. It also says he received the ACM Turing Award in 1988.

6.2 Does this make Sutherland the inventor of VR?

The sources here do not say that. They record a 1968 paper and the museum’s description of his ideas. Treat the paper as an early landmark. Do not call it the first.

7.1 What do everyday AR apps do?

IBM names several uses of AR.

• Furniture: Ikea Place lets users virtually place furniture in their homes.
• Navigation: mobile mapping apps add directional arrows and street names over the view.
• Filters: social media filters, such as Snapchat filters, alter the images seen through phone cameras in real time.
• Games: Pokemon GO blends virtual creatures and objects into real-world locations.
• Healthcare: AR can be used for medical training, surgical planning and patient education.

7.2 How does NASA use AR?

NASA’s description on Wikimedia Commons says astronaut Scott Kelly checked out a Microsoft HoloLens. This was aboard the International Space Station. It says the device is part of project Sidekick. Sidekick is exploring AR. It aims to cut crew training needs and help astronauts work more efficiently in space.

7.3 How is VR used in training?

NASA’s description of its second photo says astronaut Shane Kimbrough used a virtual reality headset. He used it to train for upcoming spacewalks. It says VR is used in training on the ground and in space. This keeps skills sharp.

A 2020 meta-analysis looked at laparoscopic surgery training. Laparoscopic surgery is operating through small cuts with a camera. The authors analysed 24 randomised controlled trials. These were published up to January 2018. The trials compared VR training with apprenticeship training.

The authors reported a clear gain in trainee skill in all their meta-analyses. They concluded that VR improves efficiency and also quality. Error rates fell and tissue handling improved.

8.1 Does the Union Budget mention this sector?

The Union Budget 2026-27 speech was delivered on 1 February 2026. Paragraph 60 is under the heading Orange Economy. It speaks about the Animation, Visual Effects, Gaming and Comics (AVGC) sector.

• The speech calls AVGC a growing industry.
• It says the sector is projected to require 2 million professionals by 2030.
• It proposes to support the Indian Institute of Creative Technologies, Mumbai.
• The support is for setting up AVGC Content Creator Labs in 15,000 secondary schools and 500 colleges.

These details are as of that speech. The speech does not name AR or VR. Treat AVGC as nearby context, not as an AR or VR scheme.

9.1 What exactly did UPSC ask?

This appeared in the Civil Services (Preliminary) Examination 2019. It was Question 91 in the Series A booklet of General Studies Paper I. The official words are below.

UPSC’s official Series A answer key gives option (b), 3 and 4, for Question 91.

See UPSC CSP 2019 GS Paper I, Q91. View this question.

9.2 What else was on the same page?

Question 95 on the same page of the booklet was about wearable technology. It asked which tasks are accomplished by wearable devices. Question 94 was about digital signatures. Both topics have their own lessons under Related Articles.

9.3 Quick Q&A