2006 exterior changes: LED rear lights, re-designed front bumper (including diff shape reflectors).
2007 exterior changes: Bonnet (to accomodate the VQ35HR engine which sits higher than the DE).
2006 Interior changes: Different leather seats, door cards, centre console (from the back of the prop tunnel all way up to the dash), stronger and better tactile plastics used
Full list of 2006 changes as from Nissan:
viewtopic.php?f=169&t=55422
Full list of 2007 changes as from Nissan:
viewtopic.php?f=169&t=55421