They both are zinc coated at the mill and are designed for rust and corrosion resistance. Both are passed through a hot dip coating process; however Galvannealed steel goes through an additional annealing process, which induces diffusion alloying between the molten zinc coating and the steel. This vastly improves the formability and paint adhesion of the Galvannealed material but leaves it with a duller matte surface compared to the spangle finish achieved with just Galvanized.…