I submitted an entry to a contest that requires the work not be published. I met that criterion. I have substantially rewritten the article - it's now six pages instead of two. Basically expanded a short work to a full chapter for a book. The contest announcements are in October. My question is, are the two works considered different or are the same since they're on the same basic topic?
It depends on the contest. If it is clearly mentioned as a part of their rules and regulations that the article should not be an extended / revised version of a published one, I would give it a skip. If it doesn't, as a matter of ethics, I would inform / confirm from the authority if it is acceptable.
I would suggest confirming with the committee now itself, as in case of a no, you still have some time left to work on a new article.
Basically it is the content that matters. No matter how long or short the article is .
The article should not be less than the minimum number of words required. If they are more, its fine.
Further, regarding the length as per my opinion ; the policy is not breached.
Still you can check this with rules and regulations of the contest.