Programming Terminology

VBA is an acronym referring to Visual Basic for Applications which is a programming language introduced in Excel in 1995 and implemented in the other Microsoft Office applications over the following four or five years.  VBA is based on the Visual Basic language, and uses the language elements and structures in Visual Basic 6.0.

XLM is an abbreviation that stands for the old eXceL Macro programming language, which was the macro programming language in Excel prior to the introduction of Visual Basic for Applications in Excel 5.

XLM is entered and stored on special Macro Worksheets. It uses a superset of functions to control application and workbook state, interact with the user and read and update the contents of workbooks.  In addition to that superset of functions, XLM also uses the standard worksheet functions, and many of those have default behavious or have optional arguments still to this day, to facilitate their use in XLM.

XLM is still supported in Excel for legacy support of old workbooks which have not been updated and can still be used and authored.  Most developers have moved on to VBA or Visual Studio for Office.