ground ball vs grounder

ground ball and grounder both are nouns.

Word	Noun	Adjective	Verb	Adverb
ground ball	Yes	No	No	No
grounder	Yes	No	No	No

As nouns, ground ball and grounder are synonyms defined as:

ground ball and grounder: (baseball) a hit that travels along the ground

Other synonyms of ground ball include groundball, hopper.

ground ball (noun)	grounder (noun)
(baseball) a hit that travels along the ground	(baseball) a hit that travels along the ground