If you thought NVIDIA's naming scheme for its desktop range of GPUs is confusing enough, wait till you see what they're calling their latest lineup of GPUs for notebooks.
In order from lowest to highest-end, we have the GeForce 9700M GT, 9700M GTS, 9800M GTS, 9800M GT and 9800M GTX. The real oddity, however, is where the 9800M GT sits above the GTS. NVIDIA really do seem to enjoy confusing people...
You can get more details on the new lineup at Tech Report.
At the top end of the new mobile GPU line, the GeForce 9800M GTX seems to have most in common with the desktop GeForce 8800 GT: both have 112 stream processors and 256-bit memory interfaces, while the 8800 GT has slightly higher memory bandwidth (57.6GB/s) and a 504 gigaFLOPS floating-point arithmetic rating. The 9800M GTS corresponds to the desktop GeForce 9600 GT in much the same way, with the same stream processor count and memory interface width, but lower memory bandwidth (51GB/s instead of 57.6GB/s) and a lower gigaFLOPS rating (240 instead of 312).