Question

It is clear that in EcmaScript, functions when invoked create a new execution context. All variables and functions defined within a function may only be accessed inside that function scope. But when we use closures variables and functions may be accessed outside that context.
IIFE is a function expression that gets invoked immediately. It is simple.

But why are IIFE different from Self-Executing Anonymus Functions, it is not completely clear to me!?

Answer 1

They are the same, it was renamed to IIFE because an IIFE is not necessarily anonymous, and they do not execute themselves.

consider the following:

(function bleh() {
    alert('I am not anonymous, i have a name!');
})(); //<-- invoked like any other function