I know this post may seem a little "nick-picking" on what happens and what things are called. My point is there are multiple settings that affect the systems that owners should be aware -- hope it is helpful to some:
Autopilot is primarily a "lane keeping" system -- maintains the lane while driving, hence the blue lines indicating the lane markings are sufficient; The speed control is Adaptive Cruise control -- maintaining the speed selected based on traffic in the lane in front of the car -- generally in moving traffic and not for stationary objects; Collision Avoidance System recognizes a quickly slowing or suddenly stopped vehicle in the path--That sudden RED vehicle avatar that appears if you begin approaching a vehicle in your path and the Tesla is not braking sufficiently (hopefully not seen too often). Collision Avoidance is active always. Adaptive cruise slowing is based on the number of car-lengths you set on the stock (cruise control rotating knob). I keep mine at 3 cars, which is enough to slow comfortably but not so far back other drivers "squeeze" in. Anything less than 3 car lengths scares the "heck" out of me.
Autopilot, with lane keeping activates the lane keeping function as well as Adaptive Cruise Control when double clicking the Cruise Control stock. When using the "double click" the systems look for several settings -- posted speed limit and the Speed Offset in the driver's profile as well as the car length setting. I set the "offset" in my profile to ZERO after discovering that if the posted speed was 50mph and the offset was +10mph the Tesla would immediately attempt to get to 60mph (posted speed and offset) when activating Cruise control function or with Autopilot. This may not be an issue on an Interstate hwy with light traffic, but can be on a surface street where I may not intend to drive 10 over the speed limit. There also appears to be a correlation with the Steering setting in the profile as well (sport vs comfort) when Auto Pilot is selected. I had mine set to sport, and the Tesla seemed to steer more trying to maintain the lane keeping function, so I set to comfort, and it appeared to correct less -- no 100% sure since there were software updates occurring that may have affected my perception.
Just keep in mind there are several systems in play when we double click what we tend to call "Autopilot" and those systems' settings are affecting the Tesla's driving, handling and our safety.