four-hitter vs 4-hitter

four-hitter and 4-hitter both are nouns.

Word	Noun	Adjective	Verb	Adverb
four-hitter	Yes	No	No	No
4-hitter	Yes	No	No	No

As nouns, four-hitter and 4-hitter are synonyms defined as:

four-hitter and 4-hitter: a game in which a pitcher allows the opposing team 4 hits

four-hitter (noun)	4-hitter (noun)
a game in which a pitcher allows the opposing team 4 hits	a game in which a pitcher allows the opposing team 4 hits