sidekick vs buddy

sidekick and buddy both are nouns.

Word	Noun	Adjective	Verb	Adverb
sidekick	Yes	No	No	No
buddy	Yes	No	No	No

As nouns, sidekick and buddy are synonyms defined as:

sidekick and buddy: a close friend who accompanies his buddies in their activities

Other synonyms of sidekick include brother, chum, crony, pal.

sidekick (noun)	buddy (noun)
a close friend who accompanies his buddies in their activities	a close friend who accompanies his buddies in their activities