Hi.
They are the same except for the electric plug. I currently have an old Garmin eTrex Vista. It does the job but it is a few years old, I got it from my father in law. For my Christmas list, I put down the Garmin GPSmap 60CSx. It is rated as the best unit out there right now, and the price reflects it. It holds on to the signal even in forested areas, which is where most units fail. The model under it, the GPSmap 60CX is also very well rated and slightly cheaper. If that is out of the price range, the Magellan eXplorist 210, at £179 or so, is one of the best in its price range.
If what you want is SatNav (for the car, to navigate roads), then I recommend a TomTom. I have the TomTom Go 910. It is their most expensive model and comes loaded with European and North American maps. It also has its own hard drive. If I had to do it again, I'd buy the cheaper 710 or 510 models. They don't have a hard drive, they operate with memory cards but they are just as good and get the job done just as well. To be honest, I don't know what I would do if I had to get around without the aid of SatNav. I love my TomTom!
Hope that helps.
June