niff vs fetor

niff and fetor both are nouns.

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

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

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

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