three-base hit vs base hit

three-base hit and base hit both are nouns.

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

As nouns, base hit is a hypernym of three-base hit; that is, base hit is a word with a broader meaning than three-base hit:

three-base hit: a base hit at which the batter stops safely at third base
base hit: (baseball) the successful act of striking a baseball in such a way that the batter reaches base safely

Other hypernyms of three-base hit include safety.

three-base hit (noun)	base hit (noun)
a base hit at which the batter stops safely at third base	(baseball) the successful act of striking a baseball in such a way that the batter reaches base safely