river red gum vs eucalyptus gum

river red gum and eucalyptus gum both are nouns.

Word	Noun	Adjective	Verb	Adverb
river red gum	Yes	No	No	No
eucalyptus gum	Yes	No	No	No

river red gum (noun)	eucalyptus gum (noun)
somewhat crooked red gum tree growing chiefly along rivers; has durable reddish lumber used in heavy construction	reddish-brown dried gummy exudation from any of several trees of the genus Eucalyptus especially Eucalyptus camaldulensis