
I don’t know what to choose. I have a standard Silverlight app hosted in an aspx page.
From the aspx page, in JavaScript, I call some methods like: FB.init() and FB.getLoginStatus().
From the silverlight app code I call the https://api.facebook.com/method/fql.query endpoint using WebClient() class.
Is it Web or Native/Desktop, and what difference does it make regarding OAuth flow, API calls and Security ?
It is web. Native desktop apps run on user computer and web run in the browser.
The difference between Oauth flows on desktop vs. web is described well in details in docs:
https://developers.facebook.com/docs/authentication/
hope this helps