What is the difference between CLBackgroundActivitySession and the current Always Allow location authorization?

I saw in https://developer.apple.com/videos/play/wwdc2023/10180/ at 12:51 that the CLBackgroundActivitySession will relaunch the app to resume location updates even if user closed the app (which I interpret to mean swiping the app from app switcher) -- despite the fact that the CLBackgroundActivitySession only require a when-in-use location permission. Since this api can give the app location updates even after the user swiped the app from the switcher, how is the api different than using the current always allow authorisation system to continuously record user movements? For the use case of continously tracking them whenever they move (let's say you wanted to record their driving behaviours), can't the app just launch the CLBackgroundActivitySession and continue to recreate this session every time the app is relaunched to keep on tracking?