buddy-buddy vs chummy

buddy-buddy and chummy both are adjectives.

Word	Noun	Adjective	Verb	Adverb
buddy-buddy	No	Yes	No	No
chummy	No	Yes	No	No

As adjectives, buddy-buddy and chummy are synonyms defined as:

Other synonyms of buddy-buddy include thick.

buddy-buddy (adjective)	chummy (adjective)
(used informally) associated on close terms	(used informally) associated on close terms
	(used colloquially) having the relationship of friends or pals