Difference between Matshita drives..?

Could somebody please tell me the difference between a Matshita DVD-RAM UJ-850S and a Matshita DVD UJ-850D
Thank you
(email address removed - imkidd57)

We have two identical AVERATEC 12.1" laptop computers and each one has a different drive. They are suppose to be a DVD RW± drive. Why would they be different. The DVD-RAm drive was in the oct. mfg. machine while the other drive was in the machine produced a month earlier in Sept. 07.

September 06, my appology

Hi. UJ-850s has DVD-RAM writing. Whereas the UJ-850D doesn’t… but it could be that your UJ-850D has been updated to the S. but otherwise they are identical drives.