We rated both as 1km max, but the basic will have an integrated antenna, with reduced performance. The current radio chipset theoretically maxes out at 3km though, and we haven't actually maxed out range ever, before maxing out distance (we have to use google earth just to find places!).

Pro will have better range due to the antenna, but the basic will get a pretty high-performing antenna too.

That pretty ambiguous. If they don't have the same range, then you shouldn't just ballpark them as both "1km max" because that doesn't really tell me anything.