Well, again it depends...but just to try and give you some kinda answer...
Assuming that both phones are of similar vintage and cost, and both are setup the same, such as both check Yahoo mail every 15 minutes, update weather every 20 minutes etc etc - all such non-OS factors being even, then I don't know of any reason one OS would use data at a rate significantly different than the other.
Does that help?
Android since v1.0. Linux user since 2001.