Should I upgrade from Quickbooks Premier 2008 to Quickbooks 2011 Premier or Pro?

I need a little help with a Quickbooks question. I need to upgrade mine to the 2011 version. I currently have the 2008 Premier Edition. My question is, what's the difference between the Premier and the Pro Editions (other than the cost)? Are they interchangeable or do I have to stay with upgrading to the Premier Edition?