Tilia japonica vs lime tree

Tilia japonica and lime tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
Tilia japonica	Yes	No	No	No
lime tree	Yes	No	No	No

As nouns, lime tree is a hypernym of Tilia japonica; that is, lime tree is a word with a broader meaning than Tilia japonica:

Tilia japonica: medium-sized tree of Japan used as an ornamental
lime tree: any of various deciduous trees of the genus Tilia with heart-shaped leaves and drooping cymose clusters of yellowish often fragrant flowers; several yield valuable timber

Other hypernyms of Tilia japonica include basswood, lime, linden, linden tree.

Tilia japonica (noun)	lime tree (noun)
medium-sized tree of Japan used as an ornamental	any of various related trees bearing limes
	any of various deciduous trees of the genus Tilia with heart-shaped leaves and drooping cymose clusters of yellowish often fragrant flowers; several yield valuable timber