The FAQ doesn't cover "how does this differ from lua", but overview contains the disclaimer:

> not all Lua features are implemented yet. Most of the dynamic parts, such as tables and handling dynamic types at runtime

It has coroutines to some extent

> At the moment Nelua does not support variable arguments in yield and resume (unlikely Lua).

It also extends lua primitives - lots of control flow things, arrays and records which look like tables but are passed by value, not by reference.

So it's an ahead of time statically typed language which looks somewhat like lua. Compiled to C, no interpreter. It says it's meta-programmable using lua which I assume is really confusing given the two languages look similar and behave differently.