With the 2010 model year, trek introduced the replacement to the jack, the ticket. With the ticket 30 being the top end of the 3 levels of tickets.
You know with other makes when they have multiple price levels the forks tend to change? Well loking at the specs, both the 30 and 20 come with a RST Launch fork with the 10 having a RST gila. The 30 has juicy 3 brakes, the 20 shimano m486 hydro brakes, the 10, shimano m416 mechanical disc brakes.
Usually when a company offers multiple levels with a dj bike all the forks on each one are different. The 20 and 10 are ok, but I find the decision to use the RST launch on the 30 is a bit pathetic. Come on trek, wisen up and put an appropriate fork like a DJ1/DJ2, Argyle, RST Space Jump on the ticket 30.