Difference between IIFE and calling a function immediately?

[christkene]

Is there any difference between and IIFE\[code\](function foo () { var var_of_concern;}());\[/code\]and a plain function\[code\]function foo () { var var_of_concern;}foo();\[/code\]The caveat that concerned me, was if I pass nothing out of either the IIFE or the function, will the IIFE keep the memory alive longer?