I haven't done the Epcot one - love the Calif one - was looking for a Soarin thread to find out how long the Epcot one will be open - going in May 2007 - does anyone know
The Epcot attraction is permanent (or as permanent as any attraction). They are identical at the moment (except for longer lines at Epcot), but rumor has it that Epcot may get a new film at some point to make it less California oriented.
I have been on both and the ride itself is the same. I like the area where you wait in line at California Adventure (CA) better than at WDW. The line at CA has pictures of famous pilots from the past and important events related to flight. I actually smelled the oranges more at Disneyland.