[ZeLpH_MyStiK]

Codes written in a programming language needs to be compiled before it is run, and once it is compiled, you may run it as many times as you want without compiling it again. However, codes written in a scripting language is interpreted at runtime, and a program is needed to interpret the code everytime it is run.
In the case of C++ and Graal:
C++ codes are compiled before it is run.
GScript codes are interpretted by the Graal Client at runtime.

I suppose that is the difference Okiesmokies is referring to.