I'm not sure how the international maps work nor how different versions are marketed for different regions. If you are mostly driving it's a matter of how much do you want to pay and what features do you want. Traffic, for example, tends to be available only in limited areas. The car units tend to not have a long battery life - they are designed to be hooked up to power source when in the car, so when on foot, battery life is not as good. I have 2 garmins, a nuvi 205W and a gpsmap 60Cx, one for driving and one for on foot.
Perhaps other forum members will chime in.