"Role-playing versus roll-playing" is one of those old saws that just will not go away. It was probably a clever zinger the first time someone said it, thirty years ago. Supposedly, the distinction being made is between people who play a "role" and people who simply "roll" their dice. Of course, the distinction is pure hypocrisy, since any non-role-player will readily note that all role-playing involves using rules in some fashion to supplement or supplant story-making decisions.
Sometimes, this conceit is used as the rallying cry for a narrativist superiority over a gamist approach, which is even more bankrupt. There is of course nothing about either approach that tells you when to roll dice and when to simply narrate.
Another point of comparision is the power-gamer versus the "real role-player". Again, the comparison falls about, as power-gaming only makes sense within the context of the imaginary world, and the "real role-player" is as constrained as anyone by the framework of the game.
The only meaningful use of the term is to distinguish between GMs who rank fiat over letting the dice fall where they may. Of course, most GMs use a mixture of approaches. Only a minority of GMs never use the rules as written, and it is essentially impossible to play a game using only the defined rules, as no gaming system can completely describe all the possible events that could happen in a game. While there may not be common ground between more freeform GMing and the "let the dice fall where they may" approach, there is also little reason for antagonism. Either approach can result in a good game.
See also rule-playing.