You can't receive Social Security retirement benefits and disability benefits at the same time (with one small exception, which we'll discuss below). The Social Security disability program exists to provide disability benefits to those who are unable to work as a result of their conditions and who are too young to draw their retirement benefits. In this sense, Social Security disability insurance (SSDI) can be thought of as a retirement benefit for those who are forced to retire early. If you do collect SSDI disability benefits, they will be converted to retirement benefits when you reach full retirement age.
The only exception is for an individual who took early retirement through Social Security, which is possible at 62, before being approved for disability benefits.
Disabled before early retirement benefits start. If an individual drew less than a full monthly retirement benefit for a period of time, and then was approved for disability benefits, Social Security will make up the difference between the early retirement amount and the full disability amount for those months the individual was disabled but receiving early retirement benefits (retroactively).
For example, say you quit work because of health probems, started to collect early retirement benefits for a time, and then applied for and got approved for disability benefits. If Social Security agreed that your disability started before you started to collect early retirement, Social Security would pay you the difference between your disability payment (which is equal to your full retirement payment) and your early retirement payment for those months that you received early retirement payments. (The difference between your early retirement payment at age 62 and your disability payment is currently 25% of your full retirement amount.) In addition, when you reach full retirement age, you would get your full retirement benefit, as if you had never opted to collect early retirement payments. Here's an example of switching from early retirement to disability.
In addition, you would get the benefit of the disability freeze, which means that your lack of income due to disability is not counted when calculating your Socal Security retirement payment from your earnings record.
Disabled after early retirement benefits start. However, if you were collecting early retirement benefits before Social Security says you were disabled, Social Security will not pay you the difference between your disability payment and the early retirement payment, and you would be paid at a less-than-full retirement rate for the rest of your life. Similarly, if Social Security denied your disability claim outright, you would continue to receive early retirement payments at the early retirement rate for the rest of your life.
While some people who quit work at age 62 purposefully apply for disability and elect early retirement at the same time, so that the early retirement payments fill the gap until the disability payments start, remember that there is no guarantee you'll be granted disability benefits, and you could be stuck collecting less than your full retirement rate for the rest of your life. Still, this can work for those people who are severely impaired and are sure that they will get disability benefits. Getting disability benefits for those over 60 is easier than for younger folks, and Social Security gives special consideration to those over 65.
If you are considering this course of action, talk to a disability lawyer, who can help you assess your financial options and your chances of winning disability benefits.