Japanese linden vs linden tree

Japanese linden and linden tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
Japanese linden	Yes	No	No	No
linden tree	Yes	No	No	No

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

Japanese linden: medium-sized tree of Japan used as an ornamental
linden 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 Japanese linden include basswood, lime, lime tree, linden.

Japanese linden (noun)	linden tree (noun)
medium-sized tree of Japan used as an ornamental	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