x y and z are the same. Slices are nS/nS'/nS2 where n is the number of layers in from side S the layer is. nSw turns every layer up to layer n with side S.
I like you know that RDBLFU notation and MES for slices.
also most people use R R2 R' R2' 2R 2R' 2R2 2R2' 3R 3R' 3R2 3R2'
4R 4R2 4R' 4R2' 5R 5R' 5R2 5R2' 6R 6R' 6R2 6R2' 7R 7R' 7R2 7R2' Rr Rr2 Rr' Rr2' for all possible notations of the right side
you see that. That is my favorite notation to use and is what I see in all those rubiks cube videos.