An annuity is a stream of periodic payments (monthly, quarterly, semi-annually, annually) made by a life insurance company. Payments can be made for a specified period of time, or for a person's entire lifetime, no matter how long that is.
Assignment occurs when the defendant or casualty insurer providing the settlement money cannot or will not own your structure. Should this happen, a separate insurer will step in to own your structure, which allows you to receive your payments tax free. This process releases the casualty insurer from the ongoing liability for the structure payments, because this liability is taken on by the new insurer. You still require the consent of the casualty insurer to have a structure.
Can be incorporated into a structure, to provide a time period during which payments will be made regardless of whether the recipient is alive or not. It is designed to provide benefits to the estate of the injured party in most cases, or to the casualty insurer in others.