Google Contacts is a way to store and organize contact information about the people you communicate with. Each contact can contain basic information like names, email addresses, and phone numbers, but can also include extended information, like physical addresses, employer, department, or job title.
Different contact types
There are 2 different types of Google Contacts. Each is managed separately and contains similar, but not identical, information. Google Apps account administrators manage the Google Apps Directory, the domain wide contacts list. Users manage their own personal contacts, called My Contacts, using theContact Manager.
Although these contact types are managed separately, the information is merged in the display. Users see a single profile for each contact entry when viewing information in the Contacts Manager or on a mobile device.
More information on each Google Contact type is given below:
- The Google Apps Directory
The Google Apps Directory lists the contact information of the domain users and Google Groups. It can also include external contacts, such as contractors or suppliers, and Calendar resources if the administrator adds them. A Google Apps account administrator manages the Google Apps Directory.
The Google Apps Directory is available to everyone within the domain only if an account administrator has enabled contact sharing. In the Contact Manager, users can search to find any domain profile, shared contact, calendar resource, or Group. Users can also browse the list of domain profiles and calendar resources (but not Groups) by clicking on the Directory link on the left navigation panel. Directory entries also appear in the autocomplete function of every Google App, such as Gmail, Docs, and Calendar, enabled for the domain. Note that it can take up to 24 hours for any changes to appear in the Directory.
- My Contacts
My Contacts is the list of people an individual user manages. Users add contacts to this list manually or by copying and saving entries from the Google Apps Directory. A user can add, edit, and delete contacts and contact groups using the Contacts Manager. My Contacts are private and cannot be shared with other users, but when a user sends email, recipients can see the names a user has saved for each contact.
Reference - Google Group Help - What is Google Contacts?