In both cases, they are official Disney brand items made for the
Disney Store and Disney Parks. As some have mentioned, the wording on the tag will be slightly different based on where it's sold and some of the versions of the characters may be slightly different. This is even the case in the parks from one store to another.
However, imo, it's basically the same thing and you'll pay the same price. Where you run into some differences are when you start buying knock-offs at other stores. Even buying a t-shirt at Wal-Mart is NOT the same as buying a Disney brand shirt. The material and quality may be different. And you won't find any of the patterns from the parks in Wal-Mart. However, you'll get much better prices for things there. They are, after all, still "Disney" because Disney has very strict copyright laws and nothing could be sold without Disney's approval, but they are certainly of cheaper quality and price.