1) Basically the FCC, BCC and HCP lattice system are the unit system in a crystal structures.

2) There are 48 systems in BCC lattice but slip plane of each is different.

3) The slip plane changes but slip direction doesn’t changes and that’s why BCC structure mostly deforms by screw dislocation.

4) But in FCC the slip plane and slip direction changes simultaneously and that’s why it under goes edge dislocation.

5) That makes the slip plane and slip direction as major parameter to differentiate the deformability of different lattice structure.

6) But in HCP there are several slip and twinning system due to symmetry of the HCP structure, but most commonly seen deformation in HCP is twinning.

7) So the Slip plane n twinning system of deformation makes HCP unique from other crystal lattice and defines the deformability of lattice.

8) So in general the slip plane slip direction and twinning system always becomes characteristic point to study the deformation of FCC, BCC and HCP lattice structure.