Completely irrelevant of course, but iirc COM is a raw binary, smaller than 64k that can be loaded into memory and started by pointing execution at offset 100h.
EXE files were larger and had to be rebased by the OS on load.
Someone tell me if i got this wrong, it's been a while!
No, you got it right: COM files were raw binary dumps of code and data, a legacy from CP/M, whereas EXE files had the MZ magic number (for Mark Zbikowski) and enough data in the header to allow relocation.
Also, COM files in VMS are the equivalent of BAT files in MS-DOS and shell scripts in Unix-like OSes.
:) .COM was (on of?) DOS executable file extension(s) - before .EXE...