Macros are like "programs".
I think the primary difference between a macro  and a program is
that a program is normally written in a sofware language that
is then "compiled" which is a process that turns english-language
commands into machine-language commands.
That's why you can't open the msword.exe file and read all of the
commands that make Word do what it does.
A macro, on the other hand, stays english-language, and
executes in a line-by-line format.

In the case of excel, "macro" is a brought term that includes
the "Sub" (subroutines) and "function"(s) that you write in
the VBA editor.