What's the difference between "Contacts" and "People details?" In Settings -> Accounts -> Google, when I tap on my Google account, I see a "Sync settings" page with a list of different Google services that can be synced (App Data, Calendar, Drive, Gmail, Google Play Books, etc.).

This list includes both "Contacts" and "People details."  What is meant by "People details" and how does this differ from "Contacts?"  

Are there any negative outcomes I would expect from disabling sync of "People details" (i.e. what would break?)
Contacts under Accounts, helps in syncing Google-Contacts (Phone contacts saved )
More on Contacts sync adapter here

People details deals with information regarding Google play games and Google+ (Game buddies and people in your circles on Google+)
More on People sync adapter here