Yet, when looking at the UI in my actual HDP (18.104.22.168-78) installation, it is shown as a single option "AD/LDAP" (which to me makes more sense, since LDAP is just a protocol to communicate with AD (not much experience with AD but that is what is seems to me)).
Can anyone with more LDAP/AD experience explain the difference? Anyone know the difference between using LDAP vs AD for Ranger integration?
As highlighted by you both screenshots/settings highlighted for AD/LDAP within Ranger differs. Please check below -
Ranger Authentication For WebUI : The above screenshot describes how to configure the authentication method that determines who is allowed to login to the "Ranger web interface". So if you integrate Ranger with either LDAP/AD then users are LDAP or AD can be used to login to Ranger WebUI with respective credentials. The setting are configured via Ambari as below - Ambari Login->Services->Ranger->Configs->Advance->" Ranger Settings"
Ranger Authentication for UNIX: The above setting configure Ranger to use Unix for user authentication. Which means user integrated from AD/LDAP can be configured within new/existing policies [within existing repositories created eg. HDFS, YARN] and access policies can be defined for those users as shown in screenshot below - If the AD/LDAP is not integrated for Ranger UNIX authentication the user will not be fetch/displayed in above "select user". This settings are configured as -
Ambari Login->Services->Ranger->Configs->"Ranger User Info""