Mobility: it is the efficient movement of people and goods that is seen as beneficial or as they key aim of policy. This is much wiser than a traffic focus because at least it helps move attention to more efficient ways of moving people and goods. This would put a high priority on collective modes of transport (eg buses, rail).
Accessibility or an 'access focus': In this perspective it is the ability to REACH opportunities that is beneficial, not movement itself. In remote rural contexts gaining access to services, goods and contacts will often require a lot of mobility. However, in many urban contexts accessibility might involve very short trips. And in places like suburban USA policy to enhance accessibility might actually require that we reduce traffic or even reduce the need to travel (or reduce mobility).