A: The Social Security Disability Insurance (SSDI) and Supplemental Security Income (SSI) programs are both run by the Social Security Administration (SSA). SSDI provides benefits to people who are unable to work because of their disabilities. To be eligible, applicants must have a qualifying work history and be disabled or blind. SSI is a needs-based program. To be eligible for SSI, applicants must have limited income and resources and be aged, disabled or blind.