LGDUP copies the local groups or local users database from a Windows Server to a Data Mover. This creates a local groups database on a Data Mover (target server) that otherwise cannot access domain-based local groups. It also replicates user and group privileges to the target server.
SHAREDUP allows you to copy CIFS shares from one CIFS file server to another. Use it when you must duplicate many shares. By using the /SD option, you can duplicate the ACLs for the shares if there are local groups or local users in the ACL. The SIDs will be translated to the target equivalent local group/user SID.
EMCOPY lets you copy a file or directory (and included subdirectories) from and to an NTFS partition, keeping security the same on the copy as on the original. EMCOPY allows you to back up the file and directory security—ACLs, owner information, and audit information—from a source directory to a destination directory without copying the file data.
EMCOPY, however, does not copy the local groups database from one computer to another. You must use LGDUP first to copy the local groups database. Therefore, when the /lg or /lu option is specified, EMCOPY initially checks whether all of the source server’s local groups exist on the target server. Even if one group is missing, EMCOPY stops and notifies you to use LGDUP first.
This document has more information about each of these utilities: