Camping is holding your ground, waiting for opponent to make his move.
Rushing is confidently moving forward ahead of camper’s gunpoint and attacking (When temporarily distracted)
To play like a pro, you must strike the right balance between both. You need not go to the opponent every time, they will come for you. Don’t get too close; just maintain decent distance and you’ll have better chances of getting the kill.
Rush too much and you will die if your opponent can predict your move (NOOB MISTAKE).
Camp too much and you will be killed by good grenades or a proper rush with shotgun.
If you will rush, do it only when you’re 100% certain you’ll get the kill. Move unpredictably, fool around with the opponent’s positions and get them exposed, or camp behind and wait for the camper to move or make him move using your grenades. It’s just a game of patience.
Either way, rushing is a very tempting factor when you are annoyed, and to control it, practise more base to base combat. Further ahead, Spots where you can camp without danger and spots where you can rush confidently will be shown for most maps as a new article, soon.