Yahoo - Altavista - All The Web

Supposed to be the same, but they show very different results

[Spelunker]

I have good top 10 Rankings in Yahoo, but sometimes they won't show up in Altavista or Alltheweb. All the sites have free inclusion.

Does anyone else have the same problem?
For example, in Altavista they show under "worldwide results", but not under "USA" results, what is the difference?

[robotsdobetter]

Yes, Yahoo! powers Altavista and AllTheWeb index, but they both still filter and change the results to their liking. Google powers AOL, but sometimes you will see different search engine results.

[Warren]

Yahoo! have said that AltaVista and Fast will be there test sites and will offer different results to that of Yahoo!

Whilst the core back end technology remains the same (Yahoo! Search Technology) the algorithm(s) applied a these various sites will be different. It provides Yahoo! with their very own sandbox to test things.