Sorry, my point was that Google's revenue numbers were not prepared according to GAAP.
The "Gross Billings" numbers include the total amount of deals "sold", including the merchants' portions. The smaller "revenues" number front-loads income that should be recorded over time i.e., by including items that should be recorded in reserves or liabilities until such items are resolved.
For example, Groupon treats as revenue all of Groupon's theoretical portion of a sale, including any amounts that it knows will have to refund and amounts that it estimates that it will have to refund. However, such items are not revenue, either b/c Groupon knows it will be refunding such items (and thus has no claim to the money), or because it expects that it may have to. Such items are supposed to be tracked in a separate account. The separate account is balanced out by a reserve account (a liability) which is removed from the books when the risk of refund has passed.