jit compiler vs aot compiler

Ahead-Of-Time(AOT) converts high level language like C. C++ or
intermediate bytecode of a language into a pre-packed and 
compiled file DURING YOUR BUILD TIME.
So no need to wait for compilation at runtime.

Just-In-Time(JIT) compiles intermediate code into machine code
during runtime as needed, then stores currently compiled code
in a cache to reuse as needed while standing by for new calls
to compile until execution is complete. Saves memory.