The let keyword in ES6

Let me understand well: if I declare the vars of varFunc() like you did in letFunc() the result doesn't change; but if I declare vars of letFunc() like those in varFunc() I get undefined. So: for es5 var I can access anywhere in the scope the variables I have declared whitin that scope (due to hoisting) but for es6 let I can access the variables only where I have declared them? Should I suppose that let's block scope is a kind of work-around to the js hoisting? Please let me know