And now found the answer to my problem:-
On the back of your iPad look for:-
iPad 2 (Wi-Fi Only)
iPad 2 (Wi-Fi/GSM)
iPad 2 (Wi-Fi/CDMA)
iPad 3 (Wi-Fi Only)
iPad 3 (Wi-Fi/GSM AT&T)*
iPad 3 (Wi-Fi/CDMA Verizon)
I can now look at a group of iPads and see which generation etc they are without turning them on or having to compare with another.
At my age it can be difficult to understand what others regard as simple!