Flake tobacco is a popular old traditional cut of pipe tobacco. Cut from large pressed cubes of tobacco, flakes retain a much more deep flavour than most shag cuts. To prepare flake for use most people rub it down to a more favourable consistency whilst others choose to smoke it as is, just rolled and placed in the chamber.
Plug is a form of pipe tobacco utilising full tobacco leaves that are pressed and then aged. The result is a brick of tobacco, highly condensed that requires slicing before smoking.