In grappling, all positions have tons of variations. There’s the guard, which comes in varieties like: open, closed, x-guard, inverted guard, spider guard… and so on. The mount is the same way: mount, high mount, s-mount…
As a beginner, an understanding of the basic positions (and if they are good or bad to be in) is paramount. As you gain experience however, subtlety matters. Today in class we worked the s-mount because there’s nothing quite so subtle as sitting on your partners chest and squeezing the air out of their lungs.