ballgame vs new ballgame

ballgame and new ballgame both are nouns.

Word	Noun	Adjective	Verb	Adverb
ballgame	Yes	No	No	No
new ballgame	Yes	No	No	No

As nouns, ballgame and new ballgame are synonyms defined as:

ballgame and new ballgame: a particular situation that is radically different from the preceding situation

ballgame (noun)	new ballgame (noun)
a field game played with a ball (especially baseball)	a particular situation that is radically different from the preceding situation
a particular situation that is radically different from the preceding situation