flooded gum vs eucalyptus

flooded gum and eucalyptus both are nouns.

Word	Noun	Adjective	Verb	Adverb
flooded gum	Yes	No	No	No
eucalyptus	Yes	No	No	No

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

flooded gum: any of several Australian gum trees growing on moist or alluvial soil
eucalyptus: a tree of the genus Eucalyptus

Other hypernyms of flooded gum include eucalypt, eucalyptus tree.

flooded gum (noun)	eucalyptus (noun)
any of several Australian gum trees growing on moist or alluvial soil	a tree of the genus Eucalyptus
	wood of any of various eucalyptus trees valued as timber