eucalyptus vs eucalyptus tree

eucalyptus and eucalyptus tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
eucalyptus	Yes	No	No	No
eucalyptus tree	Yes	No	No	No

As nouns, eucalyptus and eucalyptus tree are synonyms defined as:

Other synonyms of eucalyptus include eucalypt.

eucalyptus (noun)	eucalyptus tree (noun)
a tree of the genus Eucalyptus	a tree of the genus Eucalyptus
wood of any of various eucalyptus trees valued as timber