What is the difference between Social Security Disability and Supplement Security Income?

                                    If you work and pay into social security over the years, you may be eligible for Social Security Disability 
                                    Benefits if you have a sufficient number of work credits. For example, in 2011, you receive 1 credit 
                                    for each $1,120 in earnings, up to a maximum of 4 per year. You need 20 credits in the 10 years 
                                    immediately before you became disabled (or 5 years of work). 

                                    If you do not have sufficient work credits you may nonetheless be eligible for Supplement Security Income
                                    (SSI), which is needs-based. However, one may meet the necessary medical criteria to be determined disabled, 
                                    but assets or other sources of household income may preclude payment of benefits.