pistachio vs pistachio tree

pistachio and pistachio tree both are nouns.

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

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

pistachio and pistachio tree: small tree of southern Europe and Asia Minor bearing small hard-shelled nuts

Other synonyms of pistachio include Pistacia vera.

pistachio (noun)	pistachio tree (noun)
nut of Mediterranean trees having an edible green kernel	small tree of southern Europe and Asia Minor bearing small hard-shelled nuts
small tree of southern Europe and Asia Minor bearing small hard-shelled nuts