long pillow vs pillow

long pillow and pillow both are nouns.

Word	Noun	Adjective	Verb	Adverb
long pillow	Yes	No	No	No
pillow	Yes	No	Yes	No

As nouns, pillow is a hypernym of long pillow; that is, pillow is a word with a broader meaning than long pillow:

long pillow: a pillow that is often put across a bed underneath the regular pillows
pillow: a cushion to support the head of a sleeping person

long pillow (noun)	pillow (noun)
a pillow that is often put across a bed underneath the regular pillows	a cushion to support the head of a sleeping person

long pillow (verb)	pillow (verb)
	rest on or as if on a pillow