niff vs malodor

niff and malodor both are nouns.

Word	Noun	Adjective	Verb	Adverb
niff	Yes	No	No	No
malodor	Yes	No	No	No

As nouns, malodor is a hypernym of niff; that is, malodor is a word with a broader meaning than niff:

Other hypernyms of niff include fetor, foetor, malodour, mephitis, reek, stench, stink.

niff (noun)	malodor (noun)
an unpleasant smell	a distinctive odor that is offensively unpleasant