I know that "S" means ST microelectronics and "W"=Winbond,
Actually, this is not accurate. Nobody knows what they mean for sure, but it may refer to the mfg plant. I have a 52246S with a Winbond chip.
To answer the other question: which is better, S or W, there's no difference.
The LG drive will not burn the new 24x "Ultra-Speed" RW media, if I'm correct, it only burns 16x on the "High-Speed" 12x type media, which is a very dubious practice. The LiteOn "6" series drives will burn very high quality 24x RW discs at 24x, and "may" soon bo flashable to 32x RW speeds. (but you didn't hear that from me)
The "6" series LiteOn drives are also slightly better at burning all other types of RW media as well, IMHO.
The "5" deries LiteOn drives are the slightly older models, are very respectable and reliable drives, but will not support any of the newer RW technology like 24x burning. They also may not copy certian copy protected discs quite as well, but this is not certain.