From cruise control to no steering wheel at all
The Society of Automotive Engineers defines six levels of driving automation, L0 through L5, and the boundaries between them matter far more than marketing language suggests. L0 is no automation at all, just warnings. L1 is a single assist like adaptive cruise control or lane keeping, but not both together. L2, which covers most systems sold today including Tesla's Autopilot and GM's Super Cruise, combines steering and speed control, but the human driver must still supervise constantly and is legally responsible for the vehicle at all times.
The jump from L2 to L3 is the biggest conceptual leap in the whole scale. At L3, the car is genuinely driving itself under specific conditions, and the human can look away, but must be ready to take back control within seconds when asked. Very few systems have reached certified L3 status because that handoff requirement is legally and technically thorny: who is at fault if the human doesn't retake control in time.