Full tilt liner question

From what i know these are the differences:

Color
Flex

Other than that there is no difference if you are thinking of switching liners, just make sure you get liners that are your same boot size.

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.

So if i am offered brand new hot doggers just with a black aftermarket liner in place of the red liners it comes with for a cheaper price i should not take the offer because the liners are more than aesthetically different? or do the liners have the exact same function?

Full Tilt sells the following liners aftermarket: Performer (low end), Plush (mid), and Pro (high end).  It depends on which liner you are talking about. The liner that comes stock in the Hot Dogger is a slight step down from the aftermarket Pro, but not as much of a step as the Plush.  It's kinda in the middle.  If it's the Pro Liner that you're getting, I say go for it.