tree kangaroo vs brush kangaroo

tree kangaroo and brush kangaroo both are nouns.

Word	Noun	Adjective	Verb	Adverb
tree kangaroo	Yes	No	No	No
brush kangaroo	Yes	No	No	No

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

tree kangaroo: arboreal wallabies of New Guinea and northern Australia having hind and forelegs of similar length
brush kangaroo: any of various small or medium-sized kangaroos; often brightly colored

Other hypernyms of tree kangaroo include wallaby.

tree kangaroo (noun)	brush kangaroo (noun)
arboreal wallabies of New Guinea and northern Australia having hind and forelegs of similar length	any of various small or medium-sized kangaroos; often brightly colored