From the article:

- autopilot was not engaged, only cruise control

- the anti-collision applied brakes but not soon enough

- the driver walked away without a scratch

How do you differentiate between autopilot and cruise control in Tesla case? I assume by lane keeping engaged?

Yes - 'autopilot' is auto-steer combined with adaptive cruise control. Now, Tesla's technically do have 'dumb' cruise control that doesn't reduce speed in response to a car getting close, but that configuration is rare since you need to specifically call in to buy one without autopilot and is probably not what the article was referring to.

cruise control just keeps the speed set, as with every other vehicle. autopilot will lane-keep and adjust speed with traffic