Chanara, a senior account manager at a large digital agency, likes having an AdWords manager account. What can she do with a manager account that she can’t do with an individual account?
Upgrade multiple manager accounts
Upgrade each individual AdWords account
Use a single sign-in for all accounts
Access the AdWords Application Programming Interface (API)
If you’re an agency or someone who manages multiple AdWords accounts, a manager account is a powerful tool that could save you time. A manager account is an AdWords account that lets you easily view and manage multiple AdWords accounts — including other manager accounts — from a single location.
Read more here: https://support.google.com/adwords/answer/6139186?hl=en