Unlike the Vive and new Vive Pro, the Vive Focus doesn't need to be connected to a PC to deliver immersive virtual reality experiences. Instead, everything is done right within the headset itself.
While that is similar to what Lenovo's currently working on with its Mirage Solo Daydream headset, the Vive Focus is different for a couple of key reasons. In addition to running its own custom software rather than Google's Daydream platform, it also features "Six Degrees of Freedom" (6DoF) tracking.
Android Central's Russel Holly recently got a chance to go hands-on with the Vive Focus while attending GDC 2018, and he describes the 6DoF system as follows –
Source : https://www.androidcentral.com/htcs-vive-focus-standalone-vr-headset-coming-global-markets