What are the differences between LDAP and Active Directory?
Active Directory is a database based system that provides authentication, directory, policy, and other services in a Windows environment
LDAP (Lightweight Directory Access Protocol) is an application protocol for querying and modifying items in directory service providers like Active Directory, which supports a form of LDAP.
Short answer: AD is a directory services database, and LDAP is one of the protocols you can use to talk to it.