Unclear terms: Statement of Purpose, Academic Statement and Personal Statement
Your application is a chance for you to sell yourself, and prove to the admissions committee that they should give you money to do research.  Your personal statement should address your "background, practical experience, special interests, and career goals," but only in ways that prove you are a good researcher.

You shouldn't waste space talking about your childhood dreams, because usually those say nothing about your research potential.  Instead you should highlight parts of your personal history that would make someone want to hire you for their lab.