muscularity vs heftiness

muscularity and heftiness both are nouns.

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

As nouns, muscularity and heftiness are synonyms defined as:

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

muscularity (noun)	heftiness (noun)
possessing muscular strength	possessing muscular strength
an imaginative lively style (especially style of writing)	the property of being large in mass
the physiological state of having or consisting of muscle