orange tree vs orange

orange tree and orange both are nouns.

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

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

orange tree (noun)	orange (noun)
any citrus tree bearing oranges	orange color or pigment; any of a range of colors between red and yellow
	round yellow to orange fruit of any of several citrus trees
	any citrus tree bearing oranges
	any pigment producing the orange color

orange tree (adjective)	orange (adjective)
	of the color between red and yellow; similar to the color of a ripe orange