It is hard to get a general feel for the approximate difference even by testing, which is why one mainly resorts to figures when asked on this subject.
If you take 2 CV's into a room to battle each other, the majority of the time each player will see a different result. It desyncs nearly all the time. I know my fleet mates and I that do this regularly have given up on the idea.
For instance, loading one full wave of ftrs, at the end of the battle i had 7 ftrs left, my fleetmate had 0. On his screen my fleetmate had 5 left, and I had 0. Pretty hard to test heh?