What's the difference between command.com and cmd.exe?

• command.com is the command line shell of Windows 9x.
• cmd.exe is the command line shell of Windows NT.

Since Windows 9x is dead (hooray) you only ever use cmd.exe nowadays which is a good thing because even though it has plenty of flaws, command.com was an awful lot worse!

CMD.EXE is a command line processor for 32bit Windows. Much like MS-DOS before it, it provides a character-mode only user interface into which you can type commands to run programs. CMD.EXE is a 32 bit program that is fully a part of Windows - in fact it's what gets run when you select Command Prompt on the Windows Accessories menu.

COMMAND.COM, on the other hand, exists only for compatibility and 16bit programs. It exists solely for those programs which have not been updated since the days of MS-DOS. It's designed to run 16bit applications, and operates just like the old MS-DOS did.

Source : http://ask-leo.com/whats_the_difference_between_commandcom_and_cmdexe.html