pistil vs. carpel

pistil

noun

Botany.
  1. the ovule-bearing or seed-bearing female organ of a flower, consisting when complete of ovary, style, and stigma.
  2. such organs collectively, where there are more than one in a flower.
  3. a gynoecium.

carpel

noun

Botany.
  1. a simple pistil, or a single member of a compound pistil.