One official likened the NSA's collection authority to a van full of sealed boxes that are delivered to the agency. A court order, similar to the one revealed by the Guardian, permits the transfer of custody of the "boxes." But the NSA needs something else, a specific purpose or investigation, in order to open a particular box. The chairman of the Senate intelligence committee, Sen. Dianne Feinstein, said the standard was "a reasonable, articulatable" suspicion, but did not go into details.
Legally, the government can ask companies for some of these records under a provision of the PATRIOT Act called the "business records provision." Initially, it did so without court cognizance. Now, the FISC signs off on every request.
Armed with what amounts to a rubber stamp court order, however, the NSA can collect and store trillions of bytes of electromagnetic detritus shaken off by American citizens. In the government's eyes, the data is simply moving from one place to another. It does not become, in the government's eyes, relevant or protected in any way unless and until it is subject to analysis. Analysis requires that second order.
So, the govt and NSA distinguish between 'having the data' (receiving a van full of boxes, in the metaphor above) and 'subjecting the data to analysis' (opening a box, in the metaphor). They have a broad order for having the data, but need more specific sign-off to process or analyse the data.
This differentiation between 'having data' and 'analysing data' is not one we'd generally make in the IT world - because if they already have the boxes in their possession, how do we know they are getting the right permission before they open the boxes? How is any oversight possible in that situation?