buddy vs sidekick

buddy and sidekick both are nouns.

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

As nouns, buddy and sidekick are synonyms defined as:

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

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

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