I believe you are correct. one of the differences is the water pipe.
another difference is what kind of power supply it comes with. There is one that has a fixed temp, and one that allows you too control the temp.
$270? sure you didnt order just the injector with power supply and bowl? you might have too supply the water pipe for that price. not sure though, never ordered one... I want one...
I know the classic set up which is this
goes for about 230 with out a water pipe