.keyCode vs. .which

I thought this would be answered somewhere on Stack Overflow, but I can’t find it.

If I’m listening for a keypress event, should I be using .keyCode or .which to determine if the Enter key was pressed?

I’ve always done something like the following:

$("#someid").keypress(function(e) {
  if (e.keyCode === 13) {
    e.preventDefault();
    // do something
  }
});

But I’m seeing examples that use .which instead of .keyCode. What’s the difference? Is one more cross-browser friendly than the other?