Yes. Every FT boot model uses a different liner, albeit small changes.  The Hot Dogger liner has the "Pro" thickness but it does not have the J-Bar heel retention system found on the Classic, Konflict, Seth, or First Chair.  And as you move from Classic to Konflict to Seth/First Chair, the liners get firmer treatments which add to the boot's overall stiffness.  Unfortunately, you cannot purchase Konflict or Seth/First Chair liners aftermarket.