The suspension is set up differently and the new D40s have more ground clearance then the 22s.
More importantly for the people inside, the D40's cabin is larger than the D22, the dual cab D40 is 175mm longer than the dual cab D22, so adults can sit in the rear of the D40 without feeling cramped.
The D40's ride is smoother than the D22 and the D40 has more gadgets in it.
The D40's intercooler is a front mount, the D22's mounts above the engine and isn't as effective.
They SAY the D22 is better off-road, but both need lift kits to go through hard stuff and so you have to throw $$ at them both.
The last difference is the price - the D40 is much more expensive.