endurance contest vs labor

endurance contest and labor both are nouns.

Word	Noun	Adjective	Verb	Adverb
endurance contest	Yes	No	No	No
labor	Yes	No	Yes	No

As nouns, labor is a hypernym of endurance contest; that is, labor is a word with a broader meaning than endurance contest:

Other hypernyms of endurance contest include labour, project, task, undertaking.

endurance contest (noun)	labor (noun)
any long and arduous undertaking	productive work (especially physical work done for wages)
	any piece of work that is undertaken or attempted
	a social class comprising those who do manual labor or work for wages
	an organized attempt by workers to improve their status by united action (particularly via labor unions) or the leaders of this movement
	concluding state of pregnancy; from the onset of contractions to the birth of a child

endurance contest (verb)	labor (verb)
	undergo the efforts of childbirth
	work hard
	strive and make an effort to reach a goal