The main problem comes from the fact that the same word is used for many different situations. A dj plays records, fine ) going any further becomes very tricky. For instance, turntablism brings a new dimension to the world of djing. A turntablist uses records but you could hardly say that he(she) plays them, more to the point he(she) plays with them. Most turntablists use records that have been cut for the specific purpose of "scratching" them. Forget about playing pre-recorded music. The recorded sounds could be anything from various noises, vocal samples, single instruments etc...that are then use as a "sonic palette". The issue of music/art versus technique is not new. My perspective is that an instrument is only the tool.When talking about the great Jazz players for instance, would their technical expertise be the best perspective? I doubt it. I take it that their contribution to music as a whole would be a better place to start from. The same goes for djs, I believe. 

 "Disco Dave" the wedding Dj has very little to do with reknowned club djs, the same way that your local handyman has very little to do with Basquiat, although they both use a few brushes and some paint. A radio dj can be compared to a literary critic, giving opportunities to people to discover music they may not know about. A club dj mixes together tracks that may be of very little interest if played on their own, he then creates an experience by finding the right blend, like a cook creates a meal from the raw elements. And then it all gets mixed up when a well known club dj gets a regular spot on the radio, or the other way around. Not being the encyclopedic type, I'll have to stop here and hope that this small contribution can be of some help.