Function property vs method

Question

What practical differences are there between defining an interface method:

interface Foo {
    bar(): void;
}

and defining a property with

Answer 1

It seems that the compiler doesn't seem to care, as all of these are valid:

interface Foo1 {
    bar(): void;
}

class Foo1Class1 implements Foo1 {
    bar = () => { }
}

class Foo1Class2 implements Foo1 {
    bar() { }
}

interface Foo2 {
    bar: () => void;
}

class Foo2Class1 implements Foo2 {
    bar = () => { }
}

class Foo2Class2 implements Foo2 {
    bar() { }
}

(code in playground)

The reason for that is probably to do with how that compiles into javascript:

var Foo1Class1 = (function () {
    function Foo1Class1() {
        this.bar = function () { };
    }
    return Foo1Class1;
}());
var Foo1Class2 = (function () {
    function Foo1Class2() {
    }
    Foo1Class2.prototype.bar = function () { };
    return Foo1Class2;
}());

In both cases an instance of one of those classes will have a property named bar which is a callable function.
The difference is only that in Foo1Class2 the bar method is part of the prototype which can then be overriden by an extending class.