I think the difference is that it is fine to want to help people because you enjoy it or to serve your Lord. It is important to remember that you are not REQUIRED to. It is not your social DUTY. You would not be a bad person if you chose not to help. You should certainly never be physically forced into providing for others. Your virtue (altruism) should never be used as a weapon against you by the leeches and moochers in society. When we as a society start turning virtue (charity) into weakness and vice (covetousness) into a strength then people turn away from virtue and toward vice.
Great points by Nitzy & Lou L. My issues with Objectivism are several, but the main problem I see is that the Randians look at altruism as a force that has been imposed on humanity from outside. And if some Randian Superman comes along & breaks this spell all will be well. My point is that altruism, or the virtues & vices that make up altruism are part of human nature....and need to be grappled with as best we can. We are never going to get change what we are.