gloom vs ambiance

gloom and ambiance both are nouns.

Word	Noun	Adjective	Verb	Adverb
gloom	Yes	No	No	No
ambiance	Yes	No	No	No

As nouns, ambiance is a hypernym of gloom; that is, ambiance is a word with a broader meaning than gloom:

Other hypernyms of gloom include ambience, atmosphere.

gloom (noun)	ambiance (noun)
a feeling of melancholy apprehension	the atmosphere of an environment
a state of partial or total darkness	a particular environment or surrounding influence
an atmosphere of depression and melancholy