musculature vs midriff

musculature and midriff both are nouns.

Word	Noun	Adjective	Verb	Adverb
musculature	Yes	No	No	No
midriff	Yes	No	No	No

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

musculature: the muscular system of an organism
midriff: (anatomy) a muscular partition separating the abdominal and thoracic cavities; functions in respiration

Other hyponyms of musculature include diaphragm, esophagus, gorge, gullet, oesophagus.

musculature (noun)	midriff (noun)
the muscular system of an organism	(anatomy) a muscular partition separating the abdominal and thoracic cavities; functions in respiration
	the middle area of the human torso (usually in front)