spur wheel vs spur gear

spur wheel and spur gear both are nouns.

Word	Noun	Adjective	Verb	Adverb
spur wheel	Yes	No	No	No
spur gear	Yes	No	No	No

As nouns, spur wheel and spur gear are synonyms defined as:

spur wheel (noun)	spur gear (noun)
gear wheels that mesh in the same plane	gear wheels that mesh in the same plane