<p>For common app, you're apparently allowed to choose your own essay topic! But for Princeton, you HAVE to choose to write about 2 of the topics that they gave you! </p>
<p>This is what I have interpreted from reading the instructions of both applications. Can someone confirm me on this?</p>
<p>You are right, and that is the main reason I chose commonapp (other than the fact that it will make all my other applications easier). I had a good idea for an essay that didn't fit in with Princeton's topics (although they are pretty good), so I went with commonapp.</p>