SSD and SSI are completely separate government programs. SSD benefits are offered to disabled individuals who have earned enough income to have their benefits covered, at least in part, through contributions they have made through FICA Social Security taxes – one of the withholding taxes you see on your paycheck. There is often a significant waiting period before SSD benefits are received. SSI benefits are offered to individuals with little to no income. Therefore, many people eligible for SSI benefits are also eligible for Medicare and food stamps. Individuals who receive SSI benefits will generally receive them much sooner.