pistachio vs pistachio nut

pistachio and pistachio nut both are nouns.

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

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

pistachio and pistachio nut: nut of Mediterranean trees having an edible green kernel

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