Up to 2007 they had a low speed bus to communicate with the electronics, from 2008 they went high speed bus so things like radio's, aircon controls & steering wheel controls aren't interchangeable.
Quadra Drive II was standard on CRD's up to 2007 then it became an option.
Most obvious change was the steering wheel design change & cruse control moved to a stalk. Radio stack more integrated but centre console went cheap looking by deleting the rubber cup holder insert & going hard plastic compared to the first generation.
.
.
.
.
.
.
.
.
.
first gen console & radio stack
second gen