Alexandra:

The provenance of this creature is debatable, and Wikipedia is not the
ultimate authority. And if you trust it, then you must also question
the origin of the domestic ferret, since Wikipedia itself says that it
is somewhat in question.

In general (no absolutes here), weasels are longer and slimmer of body,
while this "siberian weasel" appears to be stockier and shorter, more
resembling a polecat (which is itself still not definitely established
as a separate species). I was only making a guess, but given the fact
that the origin of the domestic ferret is till very much a matter of
debate, I would not give much weight to the fact that Wikipedia calls
it a "weasel".

[Posted in FML 7503]