Your CSS Profile information will be sent to the colleges. The colleges will use the information on that form to compute a family contribution for their school. Schools that use the Profile have varying formulas for computing your family contribution....they will not be the same number at each of these schools. If you want a GUESSTIMATE of your family contribution, use one of the online calculators and use the Institutional Methodology...but it will only be a GUESSTIMATE. If the school(s) has it's own online calculator, use that.
FAFSA EFC is the same for all schools and it is used for awarding federally funded need based aid.
Your family contribution per the colleges using Profile information can be VERY different than your EFC per FAFSA...or it can be very close...A lot depends on your assets, and things like whether you own your own business, or the amount of your home equity or if you are divorced and there is a non-custodial parent. These last items can make your family contribution per the CSS Profile higher than with the FAFSA EFC.