fogginess vs fug

fogginess and fug both are nouns.

Word	Noun	Adjective	Verb	Adverb
fogginess	Yes	No	No	No
fug	Yes	No	No	No

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

fogginess: an atmosphere in which visibility is reduced because of a cloud of some substance
fug: (British informal) an airless smoky smelly atmosphere

fogginess (noun)	fug (noun)
the quality of being indistinct and without sharp outlines	(British informal) an airless smoky smelly atmosphere
an atmosphere in which visibility is reduced because of a cloud of some substance