There is a difference between a simple language and a small language - sometimes they are the same thing, in other cases the language is small but not necessarily simple.

The C language is a relatively small language, but has been used to write complex databases and operating systems. So is C simple or complex? Or both? (Everyone has a different opinion).

Also, there's also a distinction from the small language core (the syntax and lanuage features) and the much bigger standard library that provides additional functionality.