nightie vs nightdress

nightie and nightdress both are nouns.

Word	Noun	Adjective	Verb	Adverb
nightie	Yes	No	No	No
nightdress	Yes	No	No	No

As nouns, nightie and nightdress are synonyms defined as:

nightie and nightdress: lingerie consisting of a loose dress designed to be worn in bed by women

Other synonyms of nightie include gown, night-robe, nightgown.

nightie (noun)	nightdress (noun)
lingerie consisting of a loose dress designed to be worn in bed by women	lingerie consisting of a loose dress designed to be worn in bed by women