travail vs overexertion

travail and overexertion both are nouns.

Word	Noun	Adjective	Verb	Adverb
travail	Yes	No	Yes	No
overexertion	Yes	No	No	No

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

travail: use of physical or mental energy; hard work
overexertion: excessive exertion; so much exertion that discomfort or injury results

travail (noun)	overexertion (noun)
use of physical or mental energy; hard work	excessive exertion; so much exertion that discomfort or injury results
concluding state of pregnancy; from the onset of contractions to the birth of a child

travail (verb)	overexertion (verb)
work hard