sweat vs difficulty

sweat and difficulty both are nouns.

Word	Noun	Adjective	Verb	Adverb
sweat	Yes	No	Yes	No
difficulty	Yes	No	No	No

As nouns, difficulty is a hyponym of sweat; that is, difficulty is a word with a more specific, narrower meaning than sweat:

sweat (noun)	difficulty (noun)
use of physical or mental energy; hard work	an effort that is inconvenient
salty fluid secreted by sweat glands	the quality of being almost beyond one's ability to deal with and requiring a great effort to achieve a positive result
condensation of moisture on a cold surface
agitation resulting from active worry

sweat (verb)	difficulty (verb)
excrete perspiration through the pores in the skin