Another Sat Nav Question

[xomegaman]

My Avensis T4 has got a TNS300 Sat Nav system with the Turn By Turn display and is the DVD system under the seat with the Europe DVD map. Other than the obvious screen difference does anyone know how this differs from the full screen map display system i.e. is the under seat unit the same I wonder? Is the under seat unit the same for both or different?

thanks

Steve