Top vs Bottom and Dom vs Sub have always (ok, since the 70s at least) been somewhat conflated between who is literally physically above or below during sex, who is the more vigorous and active and penetrative during sex and who is less active and more receptive, and who is in mental control over the whole situation and who is following orders.

Switch has also ‘always’ (since the 70s/80s) been conflated between all of these, to mean a person that’s comfortable with any role along those 3 axes I just outlined… but there has always been a lack of specificity if it actually applies to all 3 axes, or just 2, or only 1.

This is why more specific terms have arisen to be more precise:

A ‘Power Bottom’ or someone who ‘Tops from the Bottom’ is the mentally dominant one, doing the active penetrating, but is physically under the other person.

A ‘Service Top’ is the mentally submissive one, who carries out the physically vigorous acts the mentally dominant one orders them to, but is usually physically above them, or forceful with them.

There are many female dommes/dominatrixes who basically demand their partners be ‘Service Tops’, but there are also many that are more physically active and penetrative.

There are many more terms that are even more niche or localized… its always useful to ask for more explicit clarification, as there has been and still exists an ambiguity with many of these terms… different people use them to mean different things, and then get quite surprised when they find out their partner doesn’t understand a word to have the meaning they intended.

Finally, ‘vers’ isn’t actually really new.

‘Versatile’ is the even older term for a Switch, that arose in amongst primarily gay men in the 70s… Switch just basically replaced it overtime, and now apparently we are switching (lol) to a concatenation of Versatile: ‘vers’.