end game vs endgame

end game and endgame both are nouns.

Word	Noun	Adjective	Verb	Adverb
end game	Yes	No	No	No
endgame	Yes	No	No	No

As nouns, end game and endgame are synonyms defined as:

end game and endgame: the final stages of a chess game after most of the pieces have been removed from the board

As nouns, end game and endgame are synonyms defined as:

end game and endgame: the final stages of an extended process of negotiation

end game (noun)	endgame (noun)
the final stages of a chess game after most of the pieces have been removed from the board	the final stages of a chess game after most of the pieces have been removed from the board
the final stages of an extended process of negotiation	the final stages of an extended process of negotiation