VBA subs are no macros. A VBA sub can be a macro, but it is not a must.
The term "macro" is only used for recorded user actions. from these actions a code is generated and stored in a sub. This code is simple and do not provide powerful structures like loops, for example Do .. until, for .. next, while.. do, and others.
The more elegant way is, to design and write your own VBA code without using the macro features!
VBA is a object based and event oriented language. Subs, or bette call it "sub routines", are started by dedicated events. The event can be the pressing of a button or the opening of a workbook and many many other very specific events.
If you focus to VB6 and not to VBA, then you can state, that there is always a main-window or main form. This form is started if you start the compiled executable "xxxx.exe".
In VBA you have nothing like this, but you have a XLSM file wich is started by Excel. You can attach some code to the Workbook_Open event. This event is generated, if you open your desired excel file which is called a workbook. Inside the workbook you have worksheets.
It is useful to get more familiar with the so called object model of excel. The workbook has several events and methods. Also the worksheet has several events and methods.
In the object based model you have objects, that have events and methods. methods are action you can do with a object. events are things that can happen to an object. An objects can contain another objects, and so on. You can create new objects, like sheets or charts.