Much more different than titles and meta tags.

If you want both to rank, you will need a substantive rewrite (using synonyms will NOT do, nor will mixing up paragraphs.

Someone I know uses a really bad language translator. They run it both ways, then get someone else to make sense of the resulting drivel, baring in mind the target Keywords. Hey presto- a complete re-write!

If you're rewriting the tags and the product descriptions you should be all set. But, as Shaddows points out, simply changing a few words won't do it. What's the threshold? Who know's. It's like good art. You'll know it when you see it. ;-)