Clarification on Apple version identification?
A general statement regarding Model Identifiers (example: iPad1,1) is first number indicates generation and the second number indicates variant. However, there are many instances where simply reading the model identifier and trying to decode it cannot identify a device.

Comprehensive lists are available at EveryI and The iPhone Wiki. Note that there are several instances of overlap (example: iPad1,1 for both WiFi and WiFi+3G models)

The model/family/"A" number (example: A1234) may also be useful in identifying a given device (though some also overlap, such as A1395 for iPad2,1 and iPad2,4).

The model/part/"M" number is even better, typically allowing identification of more specific detail.

The iPad2,2 specifically refers to the iPad 2 WiFi+3G (GSM).