Hard to say which is the better tool when it comes to the M12 RA's
Overall length is about the same but the reverse switch on the drill is definitely more user friendly IMO especially if your in tight spot.
I have both and although the head is smaller on the impact I think the RA drill is better choice for most. Even though there is slight torque twist with the drill vs the impact driver you can use standard drill bits and also don't have to listen to impact noise. Drive 5 lbs of screws and you will know what I mean. That's the same reason why I now like my Fuel M12 screwdriver over the impact driver for many chores...once the novelty wears off using an impact driver can you appreciate the quietness along with the performance of some of the other tools. Plus the M12 RA impact has little power for really loosening tight stuff within its stated range but not still is as bad the 18v model.
That said impact drivers do work exceptionally well to set screws without camming out drive heads and bits under extreme loads.
Now as much as that new M18 Rover coming looks interesting I think I have been sold on the M18 flood/spotlight with its roatating head and that will be my next useful work light.
I already have both sticks, the M12 lantern, 2 of the hex 2361 one was free gratis Milwaukee

. Also the first rocket light, the M12 spotlight and both of the basic flashlights...one for each platform.
That rover floor model floodlight with AC adapter still interests me if there is free battery offer with it too.