Windows NT 4.0 and Windows 2000 backup both use the Microsoft Tape Format (MTF), so you should be able to backup files and folders on Windows 2000 and restore them to Windows NT 4.0.
When you try the above, you receive:
Error writing alternate file data, you do not have permission to access portions of file path. Please see owner or administrator to get permission.
You have backed up a file or folder that uses a new NTFS 5.0 feature, that is NOT supported in Windows NT 4.0. These may include reparse points, sparse files, EFS, quotas, etc...