Pixel XL charges in car same speed as Google wall charger

[AC Question]

My understanding is that the Google wall charger is supposed to support USB-C Power Delivery, but it charges at the same speed as my car charger which is just a standard 5V 2.4A charger - both will charge about 1% per minute. I have two of the Google wall chargers because the wife and I got a Pixel at the same time. Both chargers and both Google cables are the same. What's the benefit of Google's charger supposed to be if it's the same speed as a standard 5V 2.4A charger?