Microsoft's HoloLens provides a unique AR experience in several ways.

The user is not blocked off from the real world; they can still see the world around them (other people, desks, chairs, and so on) through the HMD's semitransparent optics.

The HoloLens scans the user's environment and creates a 3D representation of that space. This allows the Holograms from the HoloLens to interact with objects in the room. Holographic characters can sit on couches in the room, fish can avoid table legs, screens can be placed on walls in the room, and so on.

The system is completely wireless. It's the only commercially available positional tracking device that is wireless. The computer is built into HMD with the processing power that sits in between a smartphone and a VR-ready PC.

The user can walk, untethered, in areas as large as 30 m x 30 m.

While an Xbox controller and a proprietary single-button controller can be used, the main interaction with the HoloLens is through voice commands and two gestures from the user's hand (Select and Go back).

The final difference is that the holograms only appear in a relatively narrow field of view.

Because the user can still see other people, either sharing the same Holographic projections or not, the users can interact with each other in a more natural manner: