IDK what the VS stands for officially but to me it means Value Series. cheapest PSU corsair sells. thinner wires, older platform, corners cut. the CX is the next higher up in the line-up. the green labeled units were not very much better than the VS. the new CX series is very much better and based on a newer more efficient platform.
the VS is fine if you know its limits, most do not and expect to overclock with it. for grandmas computer with the IGP the VS is a decent unit. it is an entry level unit, the basic of the basics. In this, it is what its meant to be. most reading Toms demand more from a PSU and that is why you'll nary see it as a suggestion. the CX is almost the defacto standard starting point for most of us giving advice. longer warranty, more stable, overclock a bit (it has limits too), but always a better unit than the VS.