muscle builder vs muscle-builder

muscle builder and muscle-builder both are nouns.

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

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

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

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

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