bolster vs long pillow

bolster and long pillow both are nouns.

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

As nouns, bolster and long pillow are synonyms defined as:

bolster and long pillow: a pillow that is often put across a bed underneath the regular pillows

bolster (noun)	long pillow (noun)
a pillow that is often put across a bed underneath the regular pillows	a pillow that is often put across a bed underneath the regular pillows

bolster (verb)	long pillow (verb)
add padding to
support and strengthen
prop up with a pillow or bolster