Diff between function and delegate

[Smoke Adams via Digitalmars-d-learn]

I have

alias fnc = void function(Object);
alias del = void delegate();

Does func avoid the GC? I am passing in this to Object so I don't 
technically need a delegate or a "context". I want to be sure 
that I'm actually gaining something here by doing this.

I read somewhere that delegates only require the GC when they use 
objects outside their scope. Do delegates always use the GC or 
only in certain cases?