robe-de-chambre vs dressing gown

robe-de-chambre and dressing gown both are nouns.

Word	Noun	Adjective	Verb	Adverb
robe-de-chambre	Yes	No	No	No
dressing gown	Yes	No	No	No

As nouns, robe-de-chambre and dressing gown are synonyms defined as:

robe-de-chambre and dressing gown: a robe worn before dressing or while lounging

Other synonyms of robe-de-chambre include lounging robe.

robe-de-chambre (noun)	dressing gown (noun)
a robe worn before dressing or while lounging	a robe worn before dressing or while lounging