valet de chambre vs gentleman's gentleman

valet de chambre and gentleman's gentleman both are nouns.

Word	Noun	Adjective	Verb	Adverb
valet de chambre	Yes	No	No	No
gentleman's gentleman	Yes	No	No	No

As nouns, valet de chambre and gentleman's gentleman are synonyms defined as:

valet de chambre and gentleman's gentleman: a manservant who acts as a personal attendant to his employer

Other synonyms of valet de chambre include gentleman, man, valet.

valet de chambre (noun)	gentleman's gentleman (noun)
a manservant who acts as a personal attendant to his employer	a manservant who acts as a personal attendant to his employer