For 07 there is about 20 differences listed on the Chrysler website.....

Tire Pressure Monitoring system
Fog Lights
Homelink (3) Garage Door Openers buildt in
Bright Pedals
700 amp vs 510 amp battery
Air filtering
Dual bright exhaust tips?
Heated exterior mirrors
satin door handles
power seats
heated seats
leather seats
6 vs 4 speakers / 240 watts
mats, pockets, etc.

I have to say I've really appreciated the heated seats this winter....my wife's 2LT HHR has Remote start ...she starts it at work from inside to heat it up ...but remote start can't be had with a stick(I think)....& I think the heated seats are just as good a feature as remote start!!! (saves gas).