>An ActiveX control can be very well a non-visual (non UI) component.

That is true. For example, the MS Scripting Control can be both placed on a form and can be instanced as a server. In any case, ActiveX controls are primarily visual. Even the MS Communications control is visual - at least at design time it is.

>But the ocx file is in fact a dll inside, isn't it?

A DLL is really another type of EXE right???? It's just packaged differently. Because of the packaging, different capabilities exist.

>Yes and no. Is the difference just a naming difference or are there any >differences between the interfaces supported, etc. The more I read about >ActiveX/COM/OLE/etc, the less I understand where's the difference between >ActiveX and COM. Is there any?

ActiveX is just a name. In fact, MS renounced the rights to the term ActiveX. COM is Microsofts binary object model. COM, like CORBA - is just a name. At the root of it all, I do believe ActiveX Controls are COM Compliant.

As for the differences, I think it is fairly clear. Think how differently you work with COM Servers and ActiveX Controls.