The main thing is that they are stand-alone. Erlang is also stand-alone, so I would put that more in the application category. Initially, Tcl and Lua were desi

The main thing is that they are stand-alone. Erlang is also stand-alone, so I would put that more in the application category. Initially, Tcl and Lua were designed to be attached to other programs, so they would be scripting languages. Of course, this doesn't mean that a scripting language is necessarily missing certain things that an app language has in it, this just means that the design decisions were being driven by the intended use of the language. And in some cases (such as Tcl and Lua), they were designed with more functionality than typical scripting languages, so they can also function as a standalone application language.