The S2000 filter is much smaller and resembles the older 4 cylinder filters for the D and B series motors. OTOH, the NSX filter is much longer, so they are definitely not identical.
Addendum:
Older Honda filters were made by Fram/Filtech/Honeywell. The new S2K filters coming in are made in Japan by Toki Roki, just like our long neck NSX filters. So, stick with the long neck filters, you can't go wrong.
Price wise, I haven't seen much of a difference, local dealers want ~ $10 bux for the new S2K filter and the NSX filter.