So yep, a new version of CeVIO is a thing now. It sorta got covered up by all the VOCALOID4 announcements and such.
So, the main difference here is that you buy the voices separately now rather than them all coming in a pack together.
Also, the trial for S only lasts 30 days while the FREE version of regular CeVIO lasted permanently.
(I personally don't see why they made a whole new thing, there aren't any new features or anything. They were probably just trying to get some hype going around them and got gunned down by VOCALOID once again lol)
[Info Source]
So, the main difference here is that you buy the voices separately now rather than them all coming in a pack together.

Also, the trial for S only lasts 30 days while the FREE version of regular CeVIO lasted permanently.
(I personally don't see why they made a whole new thing, there aren't any new features or anything. They were probably just trying to get some hype going around them and got gunned down by VOCALOID once again lol)
[Info Source]