Any differences between Ubi download and steam version?

[meshuggahs]

I'd also like to know from some official source are all the releases actual steam releases or not.
Now we just have a bunch of wild speculations that some are not, ie the boxed version.

We know that steam is required for online play but if all the other releases cept the steam one are not fully integrated into steam feels kinda silly buying other version than the steam one.

And if there are differences, what are they?