Yes, the wheels of the Lorenz machine were simulated by some logical circuits made of vacuum tubes. But the book I read on the subject claimed, that the circuits were quite generic (some registers and logical operations), so if wired differently, one could make the computer to perform other combinations of operations. Of course breaking Enigma is quite a complicated matter, so it is entirely possible that Colossus was not flexible enough to be wired to do that.
While Colossus may have been capable of breaking Enigma (though it is not sure, as it was a highly specialized computer), it was actually used for breaking another, more sophisticated cipher produced by a Lorenz-made machine connected to a telex machine. When encoding, the telex machine emitted a 5-bit code, which was encrypted using the Lorenz machine. For decoding the process was reversed. This type of traffic was called Fish or Tunny in Bletchley Park.
"Well I don't see why I have to make one man miserable when I can make so many men happy." -- Ellyn Mustard, about marriage