dressing gown vs robe-de-chambre

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

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

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

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

Other synonyms of dressing gown include lounging robe.

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