sweat vs elbow grease

sweat and elbow grease both are nouns.

Word	Noun	Adjective	Verb	Adverb
sweat	Yes	No	Yes	No
elbow grease	Yes	No	No	No

As nouns, sweat and elbow grease are synonyms defined as:

Other synonyms of sweat include effort, exertion, travail.

sweat (noun)	elbow grease (noun)
use of physical or mental energy; hard work	use of physical or mental energy; hard work
salty fluid secreted by sweat glands
condensation of moisture on a cold surface
agitation resulting from active worry

sweat (verb)	elbow grease (verb)
excrete perspiration through the pores in the skin