muscularity vs brawn

muscularity and brawn both are nouns.

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

As nouns, muscularity and brawn are synonyms defined as:

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

muscularity (noun)	brawn (noun)
possessing muscular strength	possessing muscular strength
an imaginative lively style (especially style of writing)
the physiological state of having or consisting of muscle