showdown vs face-off

showdown and face-off both are nouns.

Word	Noun	Adjective	Verb	Adverb
showdown	Yes	No	No	No
face-off	Yes	No	No	No

As nouns, showdown and face-off are synonyms defined as:

Other synonyms of showdown include confrontation, encounter.

showdown (noun)	face-off (noun)
a hostile disagreement face-to-face	(ice hockey) the method of starting play; a referee drops the puck between two opposing players
	a hostile disagreement face-to-face