What I think makes Dwigger different is:

1) Individual tweets can be voted on, like in Digg, which facilitates ranking,etc. As the founders said, they wanted a more ‘conversational’ version of Twitter.

2) Dwigger works with your existing Twitter account, so no need to add yet another login/password/profile to the mix.

3) Tags, in the form of their “Zeit Cloud”, are right on the home page,so you don’t have to go to a different site to follow what’s hot.

Hope this helps. Thanks for you comment!