VBscript is a very stripped-down version of Visual Basic that is run in Windows and/or
Internet Explorer. Do a "what is vbscript" search at www.google.com to find tutorials and
background: http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=what+is+vbscript
The most famous vbscript until now is the one that forwarded fake love letters all over
the world a few years ago.
Visual Basic is a programing language that makes computer programs.
VBA (Visual Basic for Applications) is a dedicated version of Visual Basic for Office that
makes it (Excel, Word, Access, ...) fully programmable. Those pieces of VBA programming
code are commonly known as "macros". VBA is far more powerful than vbscript.