gloominess vs bleakness

gloominess and bleakness both are nouns.

Word	Noun	Adjective	Verb	Adverb
gloominess	Yes	No	No	No
bleakness	Yes	No	No	No

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

Other hyponyms of gloominess include cloud, bareness, desolation, nakedness.

gloominess (noun)	bleakness (noun)
the quality of excessive mournfulness and uncheerfulness	a bleak and desolate atmosphere
The property of having a frowning or scowling appearance.
a feeling of melancholy apprehension
an atmosphere of depression and melancholy