I’ve both (older versions).
XT is noticably stiffer
Deus is almost like riding a 2.5 tyre Vs a 2.0, there’s a lot of give in those arms! It’s not noticable in use, but back to back you notice it.
XT looks crap after the first muddy ride.
Deus looks nicer and doesnt scuff/age, mine are 1000’s of miles old and could still pass as new. And the design hasn’t aged either, shimano’s looks dated almost as soon as its released.
XT is easier to fit, no ‘extra’ parts, but requires an easily lost tool
Deus fits with allen keys, but requires a handfull of plastic/metal/rubber spacers that you have to get in the right number in the right places, mine took more than was suplied in the box so needed a few more 99p plastic washers. If you’ve ever fitted a BMX chainset it’ll be a familiar trial and error process.