Q: How do you tell if your ipad mini has retina display

You can type in the serial number (Settings > General > About > Serial Number or on the back of the iPad) in on this page, and it should give you some info about it, including the model : https://selfsolve.apple.com/agreementWarrantyDynamic.do

Or you can look up the model number (on the back of the iPad) on this page : http://support.apple.com/kb/HT5452 - A1489 and A1490 are retina, A1432, A1454 and A1455 are the first gen Mini