Will someone please tell me the difference between the "alternate" ending and the theatrical one?

Rating: Null/10 (18 September 2003)

SPOILER!!!! I've watched both the theatrical release and extended version of this movie several times and I still haven't figured out what is "alternate" about the ending in the extended version. The killer is still the kid...the hooker still dies...the psychiatrist still gets killed....I don't get it. Otherwise, I thought this movie was great. Very fresh take on the psycho-killer mainstay.