American plane vs plane tree

American plane and plane tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
American plane	Yes	No	No	No
plane tree	Yes	No	No	No

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

American plane: very large spreading plane tree of eastern and central North America to Mexico
plane tree: any of several trees of the genus Platanus having thin pale bark that scales off in small plates and lobed leaves and ball-shaped heads of fruits

Other hypernyms of American plane include platan, sycamore.

American plane (noun)	plane tree (noun)
very large spreading plane tree of eastern and central North America to Mexico	any of several trees of the genus Platanus having thin pale bark that scales off in small plates and lobed leaves and ball-shaped heads of fruits