grounder vs roller

grounder and roller both are nouns.

Word	Noun	Adjective	Verb	Adverb
grounder	Yes	No	No	No
roller	Yes	No	No	No

As nouns, roller is a hyponym of grounder; that is, roller is a word with a more specific, narrower meaning than grounder:

Other hyponyms of grounder include chop, chopper.

grounder (noun)	roller (noun)
(baseball) a hit that travels along the ground	a grounder that rolls along the infield
	Old World bird that tumbles or rolls in flight; related to kingfishers
	pigeon that executes backward somersaults in flight or on the ground
	a cylinder that revolves
	a mechanical device consisting of a cylindrical tube around which the hair is wound to curl it
	a small wheel without spokes (as on a roller skate)
	a long heavy sea wave as it advances towards the shore