Facebook App management - what is the difference between App Domains (Basic) and Domain Manager (Advanced)

Question

I have multiple subdomains using Facebook Login. I found that when adding a new subdomain, adding it into App Domains list in Basic page does not enable it. Adding the subdomain into Domain Manager in Advanced page makes it work.

so question 1: what is the difference between the 2?

In another question, it says that App Domain is supposed to be where the 'server side' files are located at.

background for question 2:

I have an API and a client that uses the same Facebook app. I assume that the api's URL should be in App Domain. But for the client, all the subdomains actually use the same codebase. I use AWS CloudFront to manage the HTTP requests from all subdomains and have them use code from the same S3 bucket. So essentially, the code is actually hosted in the s3 bucket which has 'Website Hosting' enabled.

question 2: should I just add the s3 bucket hosting URL, and ignore the subdomain URL's?

Answer 1

"App Domains" contain the domains and subdomains which can be used to perform Facebook Login, Share, Canvas etc on behalf of your app. Source, source.

In "Domain Manager" you add domains that will be allowed to prefetch content, for example when you Share of point Ads at a domain. Source.

If you're using Facebook Login, you also need to add "Valid Oauth Redirect URIs" under Facebook Login / Settings as well.

Question 2: The page that makes the call to Facebook should be entered in App Domain (and possibly Domain Manager if you use Facebook Share.