brawniness vs muscularity

brawniness and muscularity both are nouns.

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

As nouns, brawniness and muscularity are synonyms defined as:

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

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