I own both. Bought the 2012 PunJibs at the end of last season so I didn't spend a lot of time on them. I just won a pair of the 2013 TW Jibs and haven't had them mounted yet.
A few noticeable differences:
Dimensions of PunJib 118-82-108
Dimensions of TW Jib 114-86-108
The contact points on the Jib TW are significantly closer to the tip and tail than compared to the PunJib.
The Jib TW has a race base, making it a tad bit faster which we all know helps on those slushy park days.
Jib TW has edges that are 1.5x thicker than the PunJib.