two-base hit vs base hit

two-base hit and base hit both are nouns.

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

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

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

Other hypernyms of two-base hit include safety.

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