Cilantro and coriander come from the same plant, coriandrum sativum. In North America, cilantro refers to the leaves and stalks, while coriander refers to the dried seeds. Cilantro has a citrusy flavor, while coriander seeds have an earthy taste with floral notes.

TIL. This explains why my sibling hates anything seasoned with coriander, as well as any inclusion of cilantro.