T-Richard
Don't fall for the 'co-pilot' label. We are all qualified with the same licence. How many bars you have on your shoulder is simply a matter of company seniority. I've changed companies a couple of times and am currently 'only' an FO (or co-pilot as the media would have it) yet I have flown with Captains who have fewer hours than I have, but have been with the company longer.
We generally refer to the 'pilot flying' and 'pilot not flying' when splitting duties on the flight deck, each has well-defined responsibilities, although on some aircraft only the left-hand seat occupant can steer the aircraft on the ground.