bodybuilding vs muscle building

bodybuilding and muscle building both are nouns.

Word	Noun	Adjective	Verb	Adverb
bodybuilding	Yes	No	No	No
muscle building	Yes	No	No	No

As nouns, bodybuilding and muscle building are synonyms defined as:

bodybuilding and muscle building: exercise that builds muscles through tension

Other synonyms of bodybuilding include anaerobic exercise, musclebuilding.

bodybuilding (noun)	muscle building (noun)
exercise that builds muscles through tension	exercise that builds muscles through tension