DL and Studios getting the same upgrades to the ride.
The queues/exteriors are different, so its hard to compare, but neither is getting "more love" than the other.
Also, the Star Tours building at DL is much harder to access for refurbishment purposes. That could add a bit of time to the schedule.
Another thought that's occurred to me regarding the different overhaul timetables: haven't they been using the Body Wars simulators in Wonders of Life at EPCOT to help with development of the new Star Tours? Would having that on our coast make installation at our Star Tours easier? As an example, say one of the Body Wars simulators has been completely converted into the StarSpeeder 1000, effects and everything, it might be relatively simple to just switch out with one of the simulators at Star Tours. Just a possibility that might help account for the shorter turnover.