It appears that are two difference set of preferences, one for Directory Service and one for Open Directory. I always thought the latter was a implementation of the former (Open Directory implements-> Director Services). Am I misunderstanding how this works in OSX, if not why are there different preferences for Directory Service (if this is just an abstraction)?
/Library/Preferences$ ls Audio DirectoryService OpenDirectory SystemConfiguration Xsan [...] (truncated)
A directory service is the software system that stores, organizes and provides access to information in a directory. In software engineering, a directory is a map between names and values. It allows the lookup of values given a name, similar to a dictionary. As a word in a dictionary may have multiple definitions, in a directory, a name may be associated with multiple, different pieces of information. Likewise, as a word may have different parts of speech and different definitions, a name in a directory may have many different types of data.
Wikipedia (Implementation Section)
Open Directory: Apple's Mac OS X Server uses a directory service named Open Directory, which implements LDAP using a customized build of OpenLDAP and integrates support for both SASL and Kerberos authentication. It uses a plugins architecture to work with other LDAPv3 directories, including proprietary solutions like Active Directory and eDirectory.