The unit cell of hexagonal-closest packing of atoms is

Hexagonal-closest packing is end-centred because atoms occupy centres of two opposite faces.

The first would result in a crystal with cubic symmetry, which may alternatively be imagined as an assembly of cubes with atoms at the corners and in the centre of each face, while the other would result in a crystal with hexagonal symmetry (known as hexagonal close-packed, or hcp) (known as face-centred cubic, or fcc).