I am guessing the differences you would find in the two would be on controversial topics, just a guess, though.
I doubt that there would be a significant difference in the representation of historical events, or just statement of facts, but I would agree with you that logic would lend itself to Wikipedia having the potential for inaccurate information or slanted wording on controversial matters.
In my experience, Wikipedia does, at least, do a good job at attempting to be impartial. Political topics almost always have some slightly slanted rhetoric, one way or the other, that goes uncaught, though.
I trust "real" encyclopedias more, but Wikipedia is often adequate.