welter vs roll over

welter is a noun but roll over is not a noun.

Word	Noun	Adjective	Verb	Adverb
welter	Yes	No	Yes	No
roll over	No	No	Yes	No

As verbs, roll over is a hypernym of welter; that is, roll over is a word with a broader meaning than welter:

welter (noun)	roll over (noun)
a confused multitude of things

welter (verb)	roll over (verb)
be immersed in	make a rolling motion or turn
roll around	re-invest (a previous investment) into a similar fund or security
toss, roll, or rise and fall in an uncontrolled way	negociate to repay a loan at a later date for an additional fee