perfect game vs baseball game

perfect game and baseball game both are nouns.

Word	Noun	Adjective	Verb	Adverb
perfect game	Yes	No	No	No
baseball game	Yes	No	No	No

As nouns, baseball game is a hypernym of perfect game; that is, baseball game is a word with a broader meaning than perfect game:

perfect game: a game in which a pitcher does not allow any opposing player to reach base
baseball game: a ball game played with a bat and ball between two teams of nine players; teams take turns at bat trying to score runs

Other hypernyms of perfect game include ball, baseball.

perfect game (noun)	baseball game (noun)
a game in which a pitcher does not allow any opposing player to reach base	a ball game played with a bat and ball between two teams of nine players; teams take turns at bat trying to score runs