Well, there are a few other differences as well. The Crosstrail's front wheel is the newer thru axel where as the DS4 is the older quick release. Not sure if it really means that much for many of us with our style of riding though.
My personal opinion about gearing for both bikes, I would rather a 44/32 crankset, but a 11-36 cassette combo. Seems both bikes are attempting to be hill climbers?
Regarding front suspension, when I inquired about the Brain Suspension, I found that it is something Specialized has used for a few years with the mountain bikes. At first there was some problems with it working well enough, but after a year or two I've heard good things on it. I did hear back from one recent Crosstrail owner whom said the Brain system works very well. Specialized did basically tell me it's the same suspension of prior years, but with the new Brain tech. So chances are the Crosstrail Expert is using the NRX like they did last year, but added the new tech. But it's new tech on a hybrid.....take that for what it maybe.....
The only real possible issue I see with the Trek's suspension, other than many people disliking Suntour suspension in general, is the switch on the handlebar. It's nice...I really agree with that, but I've heard it could break easily. It's something on a number of bikes and I have heard instances of them breaking when flipping the bike upside down to fix flats on a trail.
Regarding the brakes, they are both of equal quality, like others have stated. Any better brakes than these maybe overkill for these hybrid bikes, but a nice cool overkill.
I personally like the Tektro's better for one reason. The Tektro's have a screw that hold the brake pads in which makes it easier to change the pads or clean the pads. Where as the Shimano has the pin which can be awkward trying to bend straight and back when changing pads. But that's a minor thing to like I suppose.
On a coolness or good looking bike factor, the Trek wins. The angles of the frame are just cool looking.
The shifter on the Crosstrails are now Microshift. I'm not sure how nice they are on the Crosstrail, but have read good things. I have tried the Microshift on a Sirrus recently and frankly they were impressive. But these were a bit different Microshifts on the Sirrus than the Crosstrail.
Hope this helps on your decision. Both bikes are great bikes and ultimately you will need to figure out what you like better. Happy Shopping!