ambiance vs glumness

ambiance and glumness both are nouns.

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

As nouns, glumness is a hyponym of ambiance; that is, glumness is a word with a more specific, narrower meaning than ambiance:

Other hyponyms of ambiance include genius loci, gloom, gloominess, miasm, miasma, feel, feeling, flavor, flavour, look, smell, spirit, tone, headiness.

ambiance (noun)	glumness (noun)
the atmosphere of an environment	a gloomy ill-tempered feeling
a particular environment or surrounding influence	an atmosphere of depression and melancholy