The numbers can vary significantly. Like the differences I see in my 767 Captain purchases.
The 767-300 Base Pack and the 767-200, 767-300 Freighter & KC-767 Tanker Expansion Models order numbers are fairly short.
My 767 AWACS Expansion Model, has a long number (more of a long alpha-numeric order number).
I pretty sure that my 767 AWACS was bought through Paypal, but still using my Credit Card.
Pretty much all the rest of my purchases have been using the Credit Card in the online store, so they all look similar to the first list of 767 that I bought. Nothing much to worry about really. I don't know how the order numbers are generated, or why they differ, but they all work fine for me.