We went through all of this last year when my wife got her latest 4Runner.

The biggest difference between the Limited and other models is that the Limited is full-time 4 wheel drive. Unlike some of the Grand Cherokees with full time 4 wheel drive, it does have a low range and it can be locked in 4 high. The other major mechanical difference is the Limited has the XREAS suspension. Basically it connects shock absorbers at opposite corners for a more controlled ride. The upside, it drives and rides nice. The downside, the shocks are proprietary and cost a lot to replace.

The other stuff is cosmetics and luxury features. Real leather instead of the pleather or cloth of lesser trims. JBL stereo not available in other trims. I think it also came with a keyless start.

The TRD Pro is the hardcore off road version. Comes with everything the TRD Off-Road does plus a leveled front suspension, upgraded springs and Bilstein shocks. The KDSS system is not available on the Pro.

The TRD Off-Road is what my wife ended up getting. More off road capable than the SR-5 with the locking rear differential, crawl control, terrain management and a few other upgrades. Hers also has the KDSS suspension which is optional only on the TRD Off-Road. I highly recommend this. The KDSS basically is a self adjusting sway bar system. Makes it more off road capable by softening the sway bars and increasing articulation. More importantly it improves on road handling with stiffer sway bars and flatter cornering. It really is a huge improvement in everyday ride and handling over her previous SR-5. It's also proven to be a smoother ride when we take it off road. Hers is also the premium which includes the pleather seats and other interior upgrades.

Really can't go wrong with a 4Runner. We're on our 2nd and have had no issues with either.