pistachio nut vs pistachio

pistachio nut and pistachio both are nouns.

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

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

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

pistachio nut (noun)	pistachio (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