roll down vs descend

roll down and descend both are verbs.

Word	Noun	Adjective	Verb	Adverb
roll down	No	No	Yes	No
descend	No	No	Yes	No

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

Other hypernyms of roll down include come down, fall, go down.

roll down (verb)	descend (verb)
gather into a huge mass and roll down a mountain, of snow	come as if by falling
	move downward and lower, but not necessarily all the way
	do something that one considers to be below one's dignity
	come from; be connected by a relationship of blood, for example