iOS Server Side Validation - receipt types
In iOS 6 each IAP (in-app purchase) transaction would have its own receipt (
SKPaymentTransaction.transactionReceipt in the StoreKit API). When you send this receipt data over to their validation API, you get the former response.
In iOS 7, Apple has started using something they call the “Grand Unified Receipt”. This means that apps have one receipt that contains information about the purchase of the app itself, as well as IAPs. You use the
-[NSBundle appStoreReceiptURL] API to load this receipt data from disk (and possibly
SKReceiptRefreshRequest to get it if it doesn't seem to exist). When you send this receipt data over to their validation API, you get the latter response.
The main difference is that the former receipt format represents one IAP transaction, while the latter represents an array of them (as well as the purchase of the application itself).
See more info in the “Using Receipts to Protect Your Digital Sales” WWDC 2013 session.