Seeing as the GL V6 wasn't available after 1997, I'm assuming he's talking pre-98 vehicles.
One of the most primary differences between the two was the suspension.
http://www.contour.org/FAQ/FAQ.php?s=specs
My car appears to have the sport suspension, as it is a stiffer ride than any other vehicle I've ridden in (excepting only my old PGT and my parents' Miata). I imagine that the GL V6 (and LX V6) would have a more comfortable though softer ride mated with the strong engine, which is probably the most ideal combination for long drives.
Otherwise, I don't think there are any differences between the GL and SE V6 packages.
Chattavegas, he wasn't asking about trim levels insomuch as the V6 package availability and its differences between the trim levels.