muscle builder vs bodybuilder

muscle builder and bodybuilder both are nouns.

Word	Noun	Adjective	Verb	Adverb
muscle builder	Yes	No	No	No
bodybuilder	Yes	No	No	No

As nouns, muscle builder and bodybuilder are synonyms defined as:

muscle builder and bodybuilder: someone who does special exercises to develop a brawny musculature

Other synonyms of muscle builder include muscle-builder, musclebuilder, muscleman.

muscle builder (noun)	bodybuilder (noun)
someone who does special exercises to develop a brawny musculature	someone who does special exercises to develop a brawny musculature