As adjectives the difference between sniffy and niffy
is that sniffy is disdainful; haughty while niffy is (colloquial) having a bad smell.
sniffy
English
Adjective
(er)
Disdainful; haughty.
characterised by sniffing.
:A sniffy cold.
niffy
English
Adjective
(er)
(colloquial) Having a bad smell.
Synonyms
* (having a bad smell ):
** (standard ): fetid, stinking
** (colloquial/slang ): pongy, stinky, whiffy