Social Security and Supplemental Security disability programs are different in many ways but are both administered by the Social Security Administration and both exist to assist individuals who have a disability and meet medical criteria may qualify for benefits under either program.
Social Security Disability Insurance pays benefits to you and certain members of your family if you are "insured," meaning that you worked long enough and paid Social Security Taxes.
Supplemental Security Income pays benefits based on financial need.
Each program involves an application process and the Social Security administration gathering medical and other information to make a decision about your insurability. The Social Security Administration has a benefits eligibility screening tool, which assesses if you are eligible for benefits. http://www.benefits.gov/ssa