Well I haven't seen or heard of any SE version, certainly nVidia haven't. You may find iot is like the 'Asus 4200-128MB Deluxe' or 'Suma 4200-128MB Special Edition' which use faster RAM and guarantee faster default clocks (plus they o/c better). I'd use price as a guide and also try VisionTek's website too.
IMHO If the SE is the more expensive version then is probably uses 3.6ns RAM instead of the usual 4.0ns which would give 300/620 o/c instead of 300/550. If the SE is the cheaper version it would most likely lack DVI & TVout.