sinew vs brawn

sinew and brawn both are nouns.

Word	Noun	Adjective	Verb	Adverb
sinew	Yes	No	No	No
brawn	Yes	No	No	No

As nouns, sinew and brawn are synonyms defined as:

Other synonyms of sinew include brawniness, heftiness, muscle, muscularity.

sinew (noun)	brawn (noun)
possessing muscular strength	possessing muscular strength
a cord or band of inelastic tissue connecting a muscle with its bony attachment