Featuring a minimalist ultra-slim design, the Arc Mouse is the successor of the Arc Surface Mouse. Meanwhile, the Modern Mouse sticks to the conventional look.
https://www.notebookcheck.net/Microsoft-launches-Arc-Mouse-and-Modern-Mouse.232210.0.html
My image of modern mouse is 3D mouse or hand gestures(movement of hand/fingers in the air/on table). Would be also useful in VR games without any additional controllers.