I'll add my two cents soon but for now, here's another take from NYC Aviation on the topic of pilot vs. co-pilot.
Now on to pilot vs co-pilot. I’m not sure why or how this perception came to be, but it seems that much of the general public doesn’t think the co-pilot is a real pilot or is somehow grossly inferior to the actual “pilot pilot.” To better describe their roles, let’s get away from pilot and co-pilot, because they’re both pilots, and start with the actual industry nomenclature. We have a captain and a first officer. Both pilots have ATPs and type ratings to fly their assigned aircraft. In fact, when a captain and a first officer are paired together to fly, they typically split the flying 50/50. If the pairing has them working 4 flights together, the captain will act as flying pilot for two flights, and non-flying pilot for two flights. The primary distinction between the roles of the captain and the first officer, is that the captain carries the weight of responsibility and authority. The captain, or pilot-in-command, in addition to being proficient at flying the aircraft, also assumes the role of in-flight manager. This role of authority is often more effectively accomplished when the captain is not piloting the aircraft, especially in an abnormal or emergency situation. With the first officer at the controls, the captain is allowed to widen his or her scope of attention, to be able to gather input from all available resources – from the first officer, the flight attendants, dispatchers and air traffic controllers to determine the course of action that would result in the most positive outcome.
via NYC Aviation