NSS AD Integration and Domain Services for Windows (DSfW) are very different services, from a directory standpoint.
Also, DSfW is broader in scope than NSS AD.
NSS AD: Provides AD users with native CIFS access to NSS-based storage.
Other file services such as AFP and NetStorage are not currently supported and are unaffected.
DSfW: Provides eDirectory users with native access to Windows servers and services, including NTFS-based storage.