Within the Nutanix main infrastructure there are two main components which Administrators can use to manage their environment, those are the following:
Prism Element
Easy to use graphical interface to manage a single Nutanix Cluster, it exists as a service within your CVMs with one of them acting as a leader.
From Prism Element you can have two different authentication methods, which are local users and Active Directory accounts.
Prism Central
Additional component which can be deployed as a VM to manage multiple clusters which can be horizontally and vertically scaled to suit your environment depending on how many components such as VMs and Clusters it is required to manage.
From PC additional to both local users and AD accounts you can also configure SAML authentication using an identity provider.
If you want to know more about the authentication types here are some additional resources you can use: