red gum vs river gum

red gum and river gum both are nouns.

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

red gum (noun)	river gum (noun)
red gum tree of Tasmania	somewhat crooked red gum tree growing chiefly along rivers; has durable reddish lumber used in heavy construction
very large red gum tree
a North American tree of the genus Liquidambar having prickly spherical fruit clusters and fragrant sap
reddish-brown wood and lumber from heartwood of the sweet gum tree used to make furniture
reddish-brown dried gummy exudation from any of several trees of the genus Eucalyptus especially Eucalyptus camaldulensis