there are some differences, personally i find if i got 4bars i tend to kill the person alot quicker, i also find that famas is better with 3bar but m16 better on 4 bars, i dunno why but i just cant seem to use a m16 on 3bars lol .. i also find it annoying on 3 bars if some1 is shooting me and i run into a building and die, but on the killcam i was no where near entering the building, whereas on 4 i tend to not die and be in the bulding... just some things i have found