I asked Aggie Catholic what the difference between the Ordinariate and the Anglo-Catholic Churches in the US was. Basically the biggest historical thing is that whole groups can convert and it establishes a permanent place for Anglo-Catholics with their own bishops similar to the Eastern Groups that have their own bishops and whatnot. Before, they had to convert individually and go through RCIA classes. Plus there were only a few churches in the US, this establishes an area in England and Wales that anyone from those areas can join (and hopefully the US will be next).
Here's the article. Make sure to read the comments as well.