Google Ad Manager is a fully-integrate advertising platform
What is Google Ad Manager
Not what is commonly referred to as Google Ads. Google Ad Manager is part of Google Marketing Platform intended for large scale publishers. If you are looking to promote your own business Google Ads is the place for you. If you are looking to have ads on your website on a small scale Adsense is probably for you.
Google Ad Manager, the free version and Google Ad Manager 360, combine what was formerly know as DoubleClick for Publishers and Google Ad Exchange. If you are directly selling ad space on your website to other businesses, this is really the platform meant for you.
The benefits to using Google Ad Manager are multiple