smoothbark vs eucalyptus tree

smoothbark and eucalyptus tree both are nouns.

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

As nouns, eucalyptus tree is a hypernym of smoothbark; that is, eucalyptus tree is a word with a broader meaning than smoothbark:

smoothbark: any of several Australian eucalypts having the bark smooth except at or near the base of the trunk
eucalyptus tree: a tree of the genus Eucalyptus

Other hypernyms of smoothbark include eucalypt, eucalyptus.

smoothbark (noun)	eucalyptus tree (noun)
any of several Australian eucalypts having the bark smooth except at or near the base of the trunk	a tree of the genus Eucalyptus