vSig and vSigX are close, but there are some differences.  (Of course, the big thing is, I'm the vSigX guy, so please don't blame Eventide if there is something wrong with vSigX, blame me…)

Version 2.0 of vSigX will be a significant update.  I have switched to a cross-platform GUI development product and have changed to a web-based help system.  I'm hoping that will get us closer to having the same product on different operating systems.