应用图标（57 * 57）和大图标（512 * 512）应该是同一张图片吗？

Question

so wonder is it need to be the same picture?

it can use difference picture ?

Answer 1

(Edited) In link text stated:

When you submit your application, you must include a 512 x 512 pixel version of your application icon for display in the App Store. Although it's important that this version be instantly recognizable as your application icon, it should be subtly richer and more detailed. In other words, you should not simply scale up your application icon to create an icon for the App Store.

So I think from this follows that you can make cosmetic changes to your picture to make it look better in good resolution.
In our app we do the reverse thing - we create 512x512 artwork and use its scaled to 57x57 variant as application icon.