rock kangaroo vs wallaby

rock kangaroo and wallaby both are nouns.

Word	Noun	Adjective	Verb	Adverb
rock kangaroo	Yes	No	No	No
wallaby	Yes	No	No	No

As nouns, wallaby is a hypernym of rock kangaroo; that is, wallaby is a word with a broader meaning than rock kangaroo:

rock kangaroo: slender long-legged Australian wallabies living in caves and rocky areas
wallaby: any of various small or medium-sized kangaroos; often brightly colored

Other hypernyms of rock kangaroo include brush kangaroo.

rock kangaroo (noun)	wallaby (noun)
slender long-legged Australian wallabies living in caves and rocky areas	any of various small or medium-sized kangaroos; often brightly colored