stench vs malodor

stench and malodor both are nouns.

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

As nouns, stench and malodor are synonyms defined as:

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

stench (noun)	malodor (noun)
a distinctive odor that is offensively unpleasant	a distinctive odor that is offensively unpleasant