Difference between Visual Basic 6.0 and VBA
VBA stands for Visual Basic for Applications and so is the small "for applications" scripting brother of VB. VBA is indeed available in Excel, but also in the other office applications.
With VB, one can create a stand-alone windows application, which is not possible with VBA.
It is possible for developers however to "embed" VBA in their own applications, as a scripting language to automate those applications.
Edit: From the VBA FAQ:
Q. What is Visual Basic for Applications?
A. Microsoft Visual Basic for Applications (VBA) is an embeddable programming environment designed to enable developers to build custom solutions using the full power of Microsoft Visual Basic. Developers using applications that host VBA can automate and extend the application functionality, shortening the development cycle of custom business solutions.
Note that VB.NET is even another language, which only shares syntax with VB.
For nearly all programming purposes, VBA and VB 6.0 are the same thing.
VBA cannot compile your program into an executable binary. You'll always need the host (a Word file and MS Word, for example) to contain and execute your project. You'll also not be able to create COM DLLs with VBA.
Apart from that, there is a difference in the IDE - the VB 6.0 IDE is more powerful in comparison. On the other hand, you have tight integration of the host application in VBA. Application-global objects (like "ActiveDocument") and events are available without declaration, so application-specific programming is straight-forward.
Still, nothing keeps you from firing up Word, loading the VBA IDE and solving a problem that has no relation to Word whatsoever. I'm not sure if there is anything that VB 6.0 can do (technically), and VBA cannot. I'm looking for a comparison sheet on the MSDN though.
Here's a more technical and thorough answer to an old question: Visual Basic for Applications (VBA) and Visual Basic (pre-.NET) are not just similar languages, they are the same language. Specifically:
- They have the same specification: The implementation-independent description of what the language contains and what it means. You can read it here: [MS-VBAL]: VBA Language Specification
- They have the same platform: They both compile to Microsoft P-Code, which is in turn executed by the exact same virtual machine, which is implemented in the dll msvbvm[x.0].dll.
In an old VB reference book I came across last year, the author (Paul Lomax) even asserted that 'VBA' has always been the name of the language itself, whether used in stand-alone applications or in embedded contexts (such as MS Office):
"Before we go any further, let's just clarify on fundamental point. Visual Basic for Applications (VBA) is the language used to program in Visual Basic (VB). VB itself is a development environment; the language element of that environment is VBA."
The minor differences
Hosted vs. stand-alone: In practical, terms, when most people say "VBA" they specifically mean "VBA when used in MS Office", and they say "VB6" to mean "VBA used in the last version of the standalone VBA compiler (i.e. Visual Studio 6)". The IDE and compiler bundled with MS Office is almost identical to Visual Studio 6, with the limitation that it does not allow compilation to stand-alone dll or exe files. This in turns means that classes defined in embedded VBA projects are not accessible from non-embedded COM consumers, because they cannot be registered.
Continued development: Microsoft stopped producing a stand-alone VBA compiler with Visual Studio 6, as they switched to the .NET runtime as the platform of choice. However, the MS Office team continues to maintain VBA, and even released a new version (VBA7) with a new VM (now just called VBA7.dll) starting with MS Office 2010. The only major difference is that VBA7 has both a 32- and 64-bit version and has a few enhancements to handle the differences between the two, specifically with regards to external API invocations.