Yes, they are completely different. The GN8110 is the GNNetcom USB adapter. It is just an adapter, nothing to it.
The NTEX14AB is the OEM Nortel USB adaptor that has volumne and call control buttons. Use this one. Its big, bulky and flashy but we found they work much better with the i2050 then the GN8110
If you want I can sell you a bunch of GN8110 for cheap that I have sitting in the office.