smoothbark vs eucalyptus

smoothbark and eucalyptus both are nouns.

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

As nouns, eucalyptus is a hypernym of smoothbark; that is, eucalyptus 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: a tree of the genus Eucalyptus

Other hypernyms of smoothbark include eucalypt, eucalyptus tree.

smoothbark (noun)	eucalyptus (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
	wood of any of various eucalyptus trees valued as timber