That's a bit like asking what the difference is between a beaten up Datsun 120Y & a Porsche!

Vim has a multitude of features not offered by plain old vi:-

• Multiple windows - horizontal, vertical & tabs.
• Visual highlighting.
• Online help via the :help command.
• Record macros into a register that you can then execute.
• Undo (and redo) multiple times, rather than old vi's insane undo toggle.
• Command line history, search history.
• An entire language embedded along with a host of available functions, eg getcwd()
• Vastly expanded pattern matching.
• Word completion via ctrl-P & ctrl-N.
• A built in file navigator (a little clunky, but can be useful).
• The ESC key actually quits commands you were trying to run instead of (insanely) running them.
• Ability to run commands on all buffers, args or windows via bufdo, argdo & windo.

I could rave on for much longer than this, vim has so many more features than plain old vi that there's really no comparison.

PS - To actually use plain old vi, you'd have to be working on a legacy Unix system, e.g. Solaris (sorry guys, it's going that way). You may well be using vim when you think you're using vi, as most Linux distros simply map vi to vim. If :help works, or multiple undos work, or :version works, you're using vim, not vi!

That's a bit like asking what the difference is between a beaten up Datsun 120Y & a Porsche!

Vim has a multitude of features not offered by plain old vi:-

• Multiple windows - horizontal, vertical & tabs.
• Visual highlighting.
• Online help via the :help command.
• Record macros into a register that you can then execute.
• Undo (and redo) multiple times, rather than old vi's insane undo toggle.
• Command line history, search history.
• An entire language embedded along with a host of available functions, eg getcwd()
• Vastly expanded pattern matching.
• Word completion via ctrl-P & ctrl-N.
• A built in file navigator (a little clunky, but can be useful).
• The ESC key actually quits commands you were trying to, well, escape from instead of (insanely) running them as vi does.
• Ability to run commands on all buffers, args or windows via bufdo, argdo & windo.

I could rave on for much longer than this, vim has so many more features than plain old vi that there's really no comparison.

PS - To actually use plain old vi, you'd have to be working on a legacy Unix system, e.g. Solaris (sorry guys, it's going that way). You may well be using vim when you think you're using vi, as most Linux distros simply map vi to vim. If :help works, or multiple undos work, or :version works, you're using vim, not vi!