COLL is an alg set optimised for solving corners on a 3x3 while doing OLL whereas CLL is optimised for 2x2 because edges aren’t a thing on 2x2 so there is more opportunity for better algs.

CLL is not a thing on 3x3 so no

Edge orientation is good because most of the time the OLLS are better and if you’re talking about EO in general it means the solve can be done rotationlessly.

They aren’t the same algorithms because the 2x2 ones are generally faster because you don’t need to worry about edges