In short
Apple's car-dashboard interface that mirrors compatible iPhone apps onto the car's screen.
Apple CarPlay is a system that lets you use compatible iPhone apps — including Driving Routes — on the dashboard screen of a compatible car. Plug in (or pair wirelessly), and apps display in a car-friendly UI with voice control.
CarPlay support is what lets a learner driver run a practice route turn-by-turn on the car screen instead of glancing at a phone.
See also