Type 1 is actually the one with the buttons. It comes in it's own housing so you don't install it in the speedometer housing. The upside is it's easier to install, the downside is you have to find somewhere on the dash that you want to rest it, similar to the scanguage.
Type 2 is installed into the speedometer housing in place of the current smart display. A bit tricky the first time but well worth it. There is a small plug that you can either solder the two wires from it to the location of the button on speedometer housing or attach the wires to a new plug and then find a spot to put it. Soldering the wires to the original button keeps a clean look. You use this one button to alternate screens and settings vs the 2 buttons on the Type 1
There is a Mark 1 and Mark 2 version of the bord computer. Mark 2 allows for installation of the distribution bord. The distribution bord allows you to connect an oil pressure and oil temp sensor, and internal cabin temp sensor, voltage, and an alternate temp sensor of your choosing.
I have the Mark 2 with the distribution bord. I really like the options provided with this set up. It allows me to monitor oil pressure and temp which is great with my engine as it is modded and remapped to 100 bhp. I can also monitor voltage which I see as a plus with the extra bits I have like one touch windows, 2 extra 12volt outlets for cell phone and gps and the addition of a electric boost gauge in a 3rd pod. The others screens show RPM, Boost, fuel economy, miles left on the tank, digital speedometer, outside temp, inside temp, and an extra screen that resembles the current smart screen.
The only difference on the more expensive models is color. Cheapest being green with black. The next price range is blue with white numbers. I chose this one as I changed all my other dials to blue as well. If you are planning on keeping the current display color of amber then I would suggest choosing their newest option which is amber with black numbers. It is meant to match the current smart color layout.
Hope this helps.