[Samba] SMB and CIFS aren't they the same ?

[Net Worker]

Storage Gurus!
    Help me understand the difference between these two :)
We have some in-house application written in the early 90's that run on
Windows (NT & 2000). They have a problem talking to a network share IF the
share is on a non-windows based NAS (EMC Celerra or old Dell NAS devices and
I think even SAMBA shares).  Let me explain, from these windows clients, we
can map these network shares, read and write just file without any problems.
But from within this application,  the dialog box that opens to load the
files, does not show any folders or files that are on a mapped network drive
of a NAS device, some times the directory listings are all messed up, and
doesn't allow the user to select a folder or file to retrieve.
But it works OK, if the files are on a windows share.

Any clues as to what this app is looking for from a non-windows based CIFS
share that a Windows Share presents to the application?

thanks in advance
G