sniff out vs smell

sniff out is not a noun while smell is a noun.

Word	Noun	Adjective	Verb	Adverb
sniff out	No	No	Yes	No
smell	Yes	No	Yes	No

sniff out (noun)	smell (noun)
	the act of perceiving the odor of something
	any property detected by the olfactory system
	the faculty that enables us to distinguish scents
	the sensation that results when olfactory receptors in the nose are stimulated by particular chemicals in gaseous form
	the general atmosphere of a place or situation and the effect that it has on people

sniff out (verb)	smell (verb)
recognize or detect by or as if by smelling	become aware of not through the senses but instinctively
	emit an odor
	inhale the odor of; perceive by the olfactory sense
	smell bad
	have an element suggestive (of something)