ok, for the storm 2 and the original, the difference is a bit mot computing power, and memory, and the "soft "buttons have been incorperated into the touch screen programm. so there are no buttons outside of the touchscreen.
the diff between the tour, the bold, and the curve is mem, comp power, os, and ability. there are apps that are available on the tour, and the bold that are not on the curve. the amount of mem and comp power is amazing, (check the website for the exact numbers) and then you have new device types, so the changes between the feel of bodie styles os there also.
personnaly i would go for the tour. im not a fan of the storms, and im pretty sure that the tour is the best of the tour, bold and curve.