travail vs straining

travail and straining both are nouns.

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

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

travail (noun)	straining (noun)
use of physical or mental energy; hard work	the act of distorting something so it seems to mean something it was not intended to mean
concluding state of pregnancy; from the onset of contractions to the birth of a child	an intense or violent exertion

travail (adjective)	straining (adjective)
	taxing to the utmost; testing powers of endurance

travail (verb)	straining (verb)
work hard