Marval - 10:51 am on Oct 15, 2004 (gmt 0)
the alltheweb backlinks have always shown way more than google - there used to be a very specific dampening factor that Google used to show backlinks - only those above a PR3 would show - until about 6 months ago - when they started this new way of showing backlinks. A search here for threads on this brings up loads of threads about that.
As far as why Google decided to do this -
this post tells it all around page 13
which leads to a thread I cant seem to find thread 24369 which is where googleguy actually confirmed the restructuring of the backlinks command