3-hitter vs three-hitter

3-hitter and three-hitter both are nouns.

Word	Noun	Adjective	Verb	Adverb
3-hitter	Yes	No	No	No
three-hitter	Yes	No	No	No

As nouns, 3-hitter and three-hitter are synonyms defined as:

3-hitter and three-hitter: a game in which a pitcher allows the opposing team only 3 hits

3-hitter (noun)	three-hitter (noun)
a game in which a pitcher allows the opposing team only 3 hits	a game in which a pitcher allows the opposing team only 3 hits