red gum vs marri

red gum and marri both are nouns.

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

As nouns, red gum and marri are synonyms defined as:

Other synonyms of red gum include Eucalyptus calophylla.

red gum (noun)	marri (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