Need permissions help/overview

I'm still a little fuzzy on what each permission does. My main questions are: What controls if a user can change their name?, What is the difference between Profiles Edit and Users Edit?
I have attached the permissions for my Member group. Is there anything that should be changed security wise?
Thanks!
Permissions: http://oi57.tinypic.com/2zghpjb.jpg
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Comments
Your permission table looks okay to me, but you might be interested in this discussions:
http://vanillaforums.org/discussion/comment/219730/#Comment_219730
http://vanillaforums.org/discussion/comment/201461#Comment_201461