From my experience they are vastly different. FAFSA calcualtes your EFC based on you as an independent adult. Although you may complete parental informtion on the FAFSA, it is not used to determine your eligibility for federal financial aid. Most schools use Need Access to gather comprehensive financial information about your parents so that they can make decisions about financial need for school-administered funds (loans and grants). Schools are generally very stingy about this kind of aid.
For example, when I completed FAFSA for 1999-2000, I was told my EFC was about $1,400. When I completed Need Access and applied for school aid I was told that my EFC was $14,000. That didn't mean my parents had to contribute that money or that I couldn't borrow that money on my own, just that the school wasn't going to contribute any of its funds to that portion of my budget.
All this financial aid gets complicated, but if you have further questions I'll do my best to answer them. I'm starting 3rd year in July so I'm on my third cycle of completing all of the paperwork.
Good luck!