they serve two different purposes. the groove is a great long anhyzer and big forehand S disc that performs best in open areas. the boss is straighter with a lot more fade than the groove that works out better in wooded courses.
I like the Groove for thumbers as well as I can't seem to throw this disk the way I want. The big problem is not having enough snap for backhand. Thrown forehand, it is good for me for sidearm flex shots in the wide open.
The Boss (Champion) I didn't like at first...I think it was because I didn't have enough snap for the 175g. I do have one at 165g and I can control it a lot better.
I recently bought an R-Pro 162g Boss and love it!!! I use this for wide open fairways and can bomb it.
The boss is my go to distance disc, perfect for a head wind, or strong cross wind, great speed, long distance capability depending on arm strength and speed. I have a Groove as well, that I found actually (no name), and it can cover some distance as well but more so in the anhyser fashion as Glenn Nowell said previously.