Difference between HCP and CCP
HCP and CCP structures both consist of layers of closest packed planes of atoms. Atoms in both structures have coordination numbers of 12. However the HCP structure contains only two types of planes, with an alternating …ABAB… arrangement. A CCP structure contains three types of planes, with an alternating …ABCABC… arrangement. The two models shown differ only in the arrangements of the top layer of atoms.