tree diagram vs tree

tree diagram and tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
tree diagram	Yes	No	No	No
tree	Yes	No	Yes	No

As nouns, tree diagram and tree are synonyms defined as:

tree diagram (noun)	tree (noun)
a figure that branches from a single root	a tall perennial woody plant having a main trunk and branches forming a distinct elevated crown; includes both gymnosperms and angiosperms
	a figure that branches from a single root

tree diagram (verb)	tree (verb)
	stretch (a shoe) on a shoetree
	chase an animal up a tree
	plant with trees
	force a person or an animal into a position from which he cannot escape