It doesn\'t really matter anyway, they\'re 2 completely different things. Firstly, Karn is one artifact creature and part of the Legacy; the Kran is an entire living race. Secondly, Karn is made out of silver; the Kran are made out of Silicon. Thirdly, Karn is a very strict pacifict (following the accidental murder of a child, I believe.) And finally, Karn was actually fairly intelligent, I believe; the Kran on the other hand... Although, much of these points were already hit on in the past.
Anyway, did Urza actually make Karn? Weren\'t some parts of the Legacy (i.e. the Weatherlight) not constructed by Urza, but merely collected by him? Its been some time since I knew all these useless facts about M:tG\'s setting, so I may be mistaken.
By the way, what was the name of that goblin? Started with a \'S\', I think...