antechamber vs anteroom

antechamber and anteroom both are nouns.

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

As nouns, antechamber and anteroom are synonyms defined as:

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

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