sniff vs smell

sniff and smell both are nouns.

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

As nouns, smell is a hypernym of sniff; that is, smell is a word with a broader meaning than sniff:

Other hypernyms of sniff include smelling.

As verbs, smell is a hypernym of sniff; that is, smell is a word with a broader meaning than sniff:

sniff (noun)	smell (noun)
sensing an odor by inhaling through the nose	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 (verb)	smell (verb)
inhale audibly through the nose	become aware of not through the senses but instinctively
perceive by inhaling through the nose	emit an odor
	inhale the odor of; perceive by the olfactory sense
	smell bad
	have an element suggestive (of something)