VB is the big brother. In VB you can create standalone programs. VB6 is the
last version before .Net, and it's the version that VBA is based on.
VBA is a subset of VB, which is used inside an application, such as Excel,
Word, other MS Office products, and also some third party products. VBA
cannot build standalone applications, but it can vastly extend the
capabilities of its parent application.
VBS is a scripting language based on VB but scaled down somewhat. You can
build standalone programs in VBS.
It's possible to use VB or VBS to control a program that uses VBA, and from
VBA you can call libraries created in VB.
- Jon