bunny vs bunny rabbit

bunny and bunny rabbit both are nouns.

Word	Noun	Adjective	Verb	Adverb
bunny	Yes	No	No	No
bunny rabbit	Yes	No	No	No

As nouns, bunny and bunny rabbit are synonyms defined as:

bunny (noun)	bunny rabbit (noun)
(usually informal) especially a young rabbit	(usually informal) especially a young rabbit
a young waitress in a nightclub whose costume includes the tail and ears of a rabbit