No the main difference is that vis is written from scratch while neovim inherited an old and hard to maintain code base.

This allows vis to experiment with various ideas:

- native multiple cursors/selection support

- structural regular expression support

- different core data structure resulting in efficient large file support

- LPeg based syntax highlighting

- Lua as an in process extension language

- client/server design (not yet implemented)

without having to care about backward compatibility and legacy systems. Of course this has also some drawbacks for example there is no existing plugin ecosystem etc.