The easiest way to tell the iPad 3 and 4 apart at a glance is that the iPad 3 has the 30 pin connector for charging and syncing and the iPad 4 has the new lightning connector.
Hi Bill.... Gabriel & Scifan... chimed in @ the same time! I have the iPad 2, but I believe that you still have the 'Retina Display' - Dave (also from W-S, NC)
Thanks again to all of you! BTW... I've been using the Marware CEO case for my iPad and loved it. However, today I bought the Zagg Folio Keyboard Case... think I'll like it even better, especially since I can now carry the iPad on trips and not need the MacBookPro. Have a great weekend, every one!