Definition: “A technology that super imposes digital artefacts on users perspective typically via an intermediate device such as a screen”
Augmented Reality typically relies on a camera or 'digital window' to capture, detect and then track pre-set markers or objects over which digital content (3D objects, audio, images, videos and text) is overlaid. The more detailed the marker or object i.e. the more detection points set the more accurate the tracking as long as the lighting and environment do not interfere too much with the camera used.
Definition: “A Computer generated ‘World’ in which the user is engaged with typically via a HMD [Head Mounted Display]”
Virtual Reality sits at the polar opposite end to Augmented Reality and is designed to place the user into a digital 'world' and historically has close ties to AR as the two are branches from the same technological principle and designed with a User experience focus.
The History of Virtual Reality
The history of Virtual Reality dates back further than you may think and the principle idea of placing a person in another universe dates back decades if not longer.
In 1957 Morton Heilig built a device designed to provide a user a rich immersive experience limited by the technology available at the time but designed to essentially help 'trick' the brain into engaging with what they are shown / experience. This device was called the Sensorama and was one of the first consumer accessible devices.
In the 1960's a lot of research was being conducted into HMD (Head Mounted Displays) and how users can interact / experience digital content one of these devices known as The Sword of Damocles helped pioneer the 'VR' revolution we are currently experiencing.
Virtual Reality is NOT a new thing BUT is a more refined thing with research still ongoing and current generation headsets still having issues but a great leap on from the 1990 counterparts not so long ago.