1. Pericarp: The pericarp of a sunflower seed develops from the wall of the ovary of the flower and is a hard shell that wraps around the seed. The pericarp usually has a hard, woody texture that helps protect the seed inside and stores nutrients. The color and texture of the sunflower seed's pericarp varies from variety to variety; some are light-colored, others dark, and the surface may also have varying degrees of smoothness or wrinkledness.

2. Seed coat: The seed coat of sunflower seeds is a hard shell encapsulated outside the embryo and endosperm, and it is the outermost protective layer of the seed. The seed coat is usually hard and thick enough to protect the embryo and endosperm inside. The color of the seed coat of sunflower seeds can be light yellow, dark yellow or brown, depending on the variety. When peeling sunflower seeds, the seed coat usually needs to be peeled back to access the embryo and endosperm inside.

In a nutshell, the sunflower seed's pericarp is the hard shell that wraps around the outside of the seed, while the seed coat is a hard protective layer that encases the embryo and endosperm.