It's a little more than that. Autopilot combines adaptive cruise control (matches speed of traffic ahead), lane-centring assist (automatically turns to keep you in the middle of the lane if you drift around), automatic emergency braking (if you get too close to something at speed and it will automatically hit the breaks if you don't), and automatic lane changing (hit the signal and it changes lanes for you).
Except for the lane changing trick, none of these are new things. Adaptive cruise control has existed since the 90s (Mercedes' Distronic system), automatic lane centring since 2003 (Honda's Lane Keep Assist System), and automatic braking also became available in 2003 (Toyota's Pre-Collision System). The latter is also going to become mandatory for all new cars in the USA and EU in 2022.