muscular structure vs muscle system

muscular structure and muscle system both are nouns.

Word	Noun	Adjective	Verb	Adverb
muscular structure	Yes	No	No	No
muscle system	Yes	No	No	No

As nouns, muscular structure and muscle system are synonyms defined as:

muscular structure and muscle system: the muscular system of an organism

Other synonyms of muscular structure include musculature.

muscular structure (noun)	muscle system (noun)
the muscular system of an organism	the muscular system of an organism