Another consideration are the skid plates. I believe the trail comes with a couple skids the SR5 does not (my trail has a gas tank skid).
Granted, the factory skids aren't real beefy, but the OP is interested in differences and that's a difference I think.
Also, it was briefly mentioned earlier but the Trail is the only one that comes with:
Crawl Control Technology
Multi-Terrain Select Technology
Electronic Rear Diff Locker
A-TRAC (actually...the SR5's MIGHT have that - not sure)
Lever-actuated transfer case (the SR5's have a dial)
(Not suggesting or opining on the value of the above features so no hi-jacking! Just pointing out the differences. Haha)
As mentioned before, the trail gets unique wheels, unique rocker trim, is the only model available with KDSS, and a hood scoop (non-functional).
CAUTION - SUBJECTIVE OPINION AHEAD: Some would argue the Trail "comes" with an intrinsic ability to hold resale value better than the others due to a more limited production run and the 'cult' following that seeks them out.