AFAIK they are both at least 80% the same vehicle. I'd go with whichever looks more well-maintained.
You do realize those prices are absolutely insane, even though I am guessing you are from Canada.
I purchase cars at government auctions and then refurbish them to re-sell on eBay. Cars like the Cavalier usually get 2 or 3 bids and sell for about US $20 to $50. Heck, in October, 2003, I saw a 2002 Cavalier with 11K miles sell for $350. I was talking to the guy who bought it, he said he was going to just turn around and re-sell it....to help pay off his 2003 Cavalier that he was $7,000 in the hole for!!!
Shop around, man, shop around, and hit any and ALL auctions that you can! Any site that charges you for info on government auctions is a scam, at least in the USA, it's all public domain info that is free if you know where to ask...