Rubus australis vs bramble bush

Rubus australis and bramble bush both are nouns.

Word	Noun	Adjective	Verb	Adverb
Rubus australis	Yes	No	No	No
bramble bush	Yes	No	No	No

As nouns, bramble bush is a hypernym of Rubus australis; that is, bramble bush is a word with a broader meaning than Rubus australis:

Rubus australis: stout-stemmed trailing shrub of New Zealand that scrambles over other growth
bramble bush: any prickly shrub of the genus Rubus bearing edible aggregate fruits

Rubus australis (noun)	bramble bush (noun)
stout-stemmed trailing shrub of New Zealand that scrambles over other growth	any prickly shrub of the genus Rubus bearing edible aggregate fruits