GS vs GSX

Can anyone tell me the difference in the GS and GSX models on the 97-04 Regals? Ive never seen a GSX in person, but have seen them online. I had a standard LS.

In addition to the GS and GSX models there is the GSE model. But the GSX was a special production/edition model. Mods were done by SLP - Street Legal Performance. Mainly badging, trim, and logos, etc. However, there should be at least 3 stages or levels of performance. Depending on the stage maximum HP over the stock 240 was up to 270 HP.

Similar for the Pontiac Grand Prix models in which there was a GTX offering.