carpel vs pistil

carpel and pistil both are nouns.

Word	Noun	Adjective	Verb	Adverb
carpel	Yes	No	No	No
pistil	Yes	No	No	No

As nouns, pistil is a hypernym of carpel; that is, pistil is a word with a broader meaning than carpel:

carpel: a simple pistil or one element of a compound pistil
pistil: the female ovule-bearing part of a flower composed of ovary and style and stigma

carpel (noun)	pistil (noun)
a simple pistil or one element of a compound pistil	the female ovule-bearing part of a flower composed of ovary and style and stigma