Atlas is a Windows version designed for gamers. Atlas users can enjoy higher framerate, lowered input delay & latency. Great for people on a low-end system, or high-end gaming machine.
I had no idea people still did this – create custom versions of Windows ISOs and try to pawn them off as something special. The legality of this is more than dubious, of course, and you can probably achieve the same results with some of the countless scripts that are out there that also remove services, telemetry and pointless applications.