anteroom vs antechamber

anteroom and antechamber both are nouns.

Word	Noun	Adjective	Verb	Adverb
anteroom	Yes	No	No	No
antechamber	Yes	No	No	No

As nouns, anteroom and antechamber are synonyms defined as:

Other synonyms of anteroom include entrance hall, foyer, hall, lobby, vestibule.

anteroom (noun)	antechamber (noun)
a large entrance or reception room or area	a large entrance or reception room or area