Extended leather do not cover lower doors, underneath the dash, and no double stitching on the doors or dash
And I believe its all using Merino Leather, full Merino leather covers basically every single area you can touch/reach.
I've had extended on my 650 which was very luxurious Nappa leather, but Full leather takes it to a whole new level, leather everywhere as my girlfriend says
For example :
Driving assistance panel (left side under the steering wheel)
Full : Merino leather wrapped
Extended : soft touch material
Dashboard (above instrument cluster)
Full : double stitched Merino
Extended : no contrast stitching
Doors (Upper arm rest beside window)
Full : double stitched Merino
Extended : no contrast stitching
Doors (lower cubby)
Full : double stitched Merino
Extended : soft touch material
lower center console (left of temp controls and the trim underneath/beside the drive selector)
Full : Merino leather
Extended : soft touch material
Glovebox
Full : leather
extended : soft touch material