I'm sympathetic to Aileen Wuornos's awful story and I've seen both of these. They're both by Nick Broomfield and both sensationalist and exploitative IMO, but if memory serves, the first gives more biographical information; the second is mostly about Nick Broomfield. But they're valuable and interesting enough. An honorable Aileen W documentary has yet to be made IMO.
Aileen W and her story were glammed up quite a bit for the movie, much more than Charlize glammed down. An opera about her life was made:
Wuornos. There's also a movie about her with Jean Smart, but I havent seen it:
Overkill: The Aileen Wuornos Story (http://www.imdb.com/title/tt0105082/' - broken link)
Here's some very detailed information on Aileen:
Aileen Carol Wuornos #805