Virtual reality is about virtual worlds that replace the real world, using VR headsets. The real world disappears and you enter a virtual reality.
Augmented reality is about adding a layer of virtual data to the real world. Tablets and smartphones allow this using the integrated camera, like for Pokemon Go. Devices like the Microsoft Hololens or the Google Glasses also falls into this category.
Mixed reality often describes experiences mixing real and virtual worlds, as when you merge virtual and real objects to provide feedback. Video where the real player is seen inside the virtual world are also called "mixed reality footages".
DFM VR provides its expertise in all those fields.