The key difference here is whether the language allows closure over the lexical environment, not whether the lexical environment contains anything used. You ca

The key difference here is whether the language allows closure over the lexical environment, not whether the lexical environment contains anything used. You can see this in Ruby where methods don't close over the environment, but blocks do, clearly Ruby methods aren't closures, not even when reïfied into a Method, whereas blocks are closures.