Authentication is the capacity for a system to ensure that who you claim to be is who you are and that you belong to the system users. This is usually realized using credentials like a login/password pair.
This pair can be managed by Neo4j or another system to which Neo4j will communicate the pair and receive a result leading to the user entering or not entering the system. These other specialized systems can be directories of the following technologies:
- LDAP
- Active directory
- Kerberos (along with LDAP)
Authorization is the capacity for a system to give different levels of access to different users, from being allowed to perform inconsequential commands like changing one's password to being allowed to add users or modify the graph. In most systems, this is achieved through the use of roles.