Life insurance names a beneficiary. It passes separate from that of an estate because the policy names the person whom the proceeds are distributed. It does not require the state to intervene to determine whom that person is -- because the person is named. In probate, typically the distributees (people whom property will be distributed) are not named, e.g. "intestate" situations where there is no will, and the court steps in to ensure the distributees under the law receive the proceeds. There are other circumstances as well but you get the picture.