Augmented Reality is widely used in the commercial sector to add a single piece of virtual information to a specific point in reality. This point is called “marker” and tells the device (through which you are looking) that a specific virtual element belongs to this place. You can view the augmented real world through some kind of glasses, but also through your phone.
Mixed Reality is a term coined by Microsoft and it differs from Augmented Reality regarding the “melding” of reality and virtuality. An MR device (like the Microsoft HoloLens) allows you to ‘anchor’ objects in the real world, independent from any special marker.