The Xplorer will cost less, be faster stock, a lot faster with a few goodies, and an excellent quad if you are ok with the 2-stroke.
The Kodiak is smaller, lighter, turns better, is smooth and refined, and a great quad that I would love to own. But it costs a little more than a 400 quad should cost.
You could not go wrong with either, it would be hard to pick for me.

 

Comparing apples and oranges again? Not sure which is faster, but buy an Xplorer and let's race!

 

They both run at about 60 to 65MPH, not only the best but the fastest utilitys made too.

2000 SCRAMBLER 400 2X4

SCRAMDADDY400