malodor vs odor

malodor and odor both are nouns.

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

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

malodor: a distinctive odor that is offensively unpleasant
odor: the sensation that results when olfactory receptors in the nose are stimulated by particular chemicals in gaseous form

Other hypernyms of malodor include odour, olfactory perception, olfactory sensation, smell.

malodor (noun)	odor (noun)
a distinctive odor that is offensively unpleasant	any property detected by the olfactory system
	the sensation that results when olfactory receptors in the nose are stimulated by particular chemicals in gaseous form