Passbook passes are just collection of data that get rendered into a card and displayed in Apple's Passbook app. Think of the Passbook files like the HTML, CSS, and JavaScript data that makes up a webpage, and the Passbook app like the browser that renders the actual page. It looks like Windows Phone 8 is taking the same data and rendering a similar card out of it, and then pushing that card to Microsoft Wallet.
Passbook passes are just collection of data that get rendered into a card and displayed in Apple's Passbook app. Think of the Passbook files like the HTML, CSS, and JavaScript data that makes up a webpage, and the Passbook app like the browser that renders the actual page. It looks like Windows Phone 8 is taking the same data and rendering a similar card out of it, and then pushing that card to Microsoft Wallet.