There is no difference (more aggressive transmission settings, cooler, different gearing, gain controller, bigger radiator, heavier springs, or bigger battery).
I tow rarely with my 4Runner. It's not designed/optimized for it.
The 'Runner tows fine, although if you want to go heavy I'd recommend some changes from stock. It's certainly not an ideal tow vehicle, but most of us need our vehicles to wear multiple hats, i.e., my family hauler/grocery getter is also my tow rig. My daily driver is also my track car.
I don't have the space or money to have a dedicated tow vehicle, otherwise I'd probably own a Tundra for the purpose. Likewise if I towed very often, I'd likely make a "proper" TV a priority (after all, you can squeeze a family into a double-cab full-size pickup).