Offense in the NFL is almost completely rooted in the Bill Walsh West Coast or Don Corywell (also west coast) offense. Defense is a little more diverse, but not much. You have the guys who want to sit back in a soft zone and make the defense go to the length of the field, the blitz maniacs, and the man coverage guys. The are obviously different branches to each. For example, the soft zone guys can come from the Pete Carroll Cover-3, Tampa-2, or Vic Fangion quarters/Cover-6 trees and sometimes a coach,like Brian Flores, will jump off the Cover-1 tree onto the blitz maniac tree.