Extranet:
An extranet is a private network that uses Internet technology and the public telecommunication system to securely share part of a business’s information or operations with Suppliers, vendors, partners, customers, or other businesses.
Intranet:
An Intranet is a website used by organizations to provide a place where employees can access company information (Eg: policies, procedures, staff, directory, department info), tools (quick links to common apps, forms etc…) and (collaborate to social sharing tools similar facebook).