You can't buy them online, OR at the ticket kiosks outside the gates of the park!
I found this very interesting - (as I am a frequent WDW visitor, but got the visit
Disneyland 2 times this spring - and am going again soon!) - You can't buy the Premium Annual Pass at the Kiosks. You have to buy a one day ticket, and go inside the park to upgrade it to a PAP.
My transaction took a little longer than 30 minutes as I had gift cards that I was also redeeming as part of the purchase.
At Disneyland, they take your picture - and every time you enter the gates at Disneyland, your picture pops up on the screen for them to confirm that it is indeed YOU coming into the park.
I haven't used my AP at WDW yet, but they were sure to tell me that before I do go to use it, that I will need to stop by guest services OUTSIDE the gates at WDW to get my fingerprint scan digitally attached to the card.
WDW Tickets use a coded magnetic strip on the rear of the card, while DLR uses a thin-line barcode on the rear of the card.
While on the face it seems that one would be just as good as the other, but I quickly found that that wasn't true at all!
Every time I went to get a Fastpass at DLR I had to jiggle the card, change kiosks, put it in, take it out, wait a few seconds and try again. At WDW the kiosk TAKES your card mechanically, where at DLR you just insert the card into a manual slot that is lined up with a red laser scanned on the inside of the slot. It seems antiquated compared to the efficiency of the ticket system at WDW.
IMHO, the magnetic strip at WDW is far more effective than the alternate system at DLR - BUT that information is based on two visits!
Hope the info helps some!