I think there is no such thing as a tumbler, the first I heard of it was the mixing service called Bitcoin Tumbler, prior to that everyone called it a mix. There are two types of financial mix. The first type works like this: A bunch of people send coins to the mix, each of the users from one of their accounts. Then the mix sends bitcoins out to a different account. I would call this a traditional mix I suppose. The mix operator themselves can link accounts. Blind mixes work in essentially the same way, a bunch of people send coins to the mix, each of the users from one of their accounts. The difference is that they get a blind signature signed certificate saying they are owed one bitcoin for every bitcoin they put in (if the mix operator is generous and does not tax them). Now they can either cash the blind certificates out to separate bitcoin accounts, or they can use them as a new form of currency with the vendors they work with. This type of mix is unlinkable by anyone. Both are still weak to amount in : amount out correlation attacks, if proper care is not taken.