ipad mini 4 models

As i am shopping online for a Mini 4 with WiFi + Cellular, I am seeing many different models. The A1550, the MNWQ2LL/A, and the MK882LL/A and so on. Very confusing but I know that there has to be a reason such as the amount of memory or RAM etc,, What I am looking for is a Mini 4 with cellular...