I'm only aware of the road and mtb versions, guessing these are them. It's probably all marketing as to the 'differences'. I think I have the mtb version and it works very well. I'd say it works as well as a floor pump, taking only a few extra pumps. The footpeg works to keep it on the ground. This is a very well thought out pump.
It is larger than many of the mini pumps out on the market. But in contrast, this one actually works, and fast. Gauge too, nice touch.
The one with gauge is better. The Nasbar one look like without gauge. Maybe they have the other model elsewhere. Topeak have some model without gauge. I don't see why anyone would want not to have a gauge and not know what pressure they are at. Take the one with gauge.