three-base hit vs three-bagger

three-base hit and three-bagger both are nouns.

Word	Noun	Adjective	Verb	Adverb
three-base hit	Yes	No	No	No
three-bagger	Yes	No	No	No

As nouns, three-base hit and three-bagger are synonyms defined as:

three-base hit and three-bagger: a base hit at which the batter stops safely at third base

Other synonyms of three-base hit include triple.

three-base hit (noun)	three-bagger (noun)
a base hit at which the batter stops safely at third base	a base hit at which the batter stops safely at third base