red gum vs Eucalyptus calophylla

red gum and Eucalyptus calophylla both are nouns.

Word	Noun	Adjective	Verb	Adverb
red gum	Yes	No	No	No
Eucalyptus calophylla	Yes	No	No	No

As nouns, red gum and Eucalyptus calophylla are synonyms defined as:

Other synonyms of red gum include marri.

red gum (noun)	Eucalyptus calophylla (noun)
red gum tree of Tasmania	very large red gum tree
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