Learning javascript. Why first code is giving error where as second is not? In first code why this is being considered as window{} where as in second it is doing what it meant to do?

1st

const tahoe = {
        mountains: ["Freel", "Rose", "Tallac", "Rubicon", "Silver"],
        print: function(delay = 1000) {
            setTimeout(function() {
                console.log(this.mountains.join('  '));
            }, delay);
        }
    };
    tahoe.print();

2nd

const tahoe = {
            mountains: ["Freel", "Rose", "Tallac", "Rubicon", "Silver"],
            print: function(delay = 1000) {
                setTimeout(()=> {
                    console.log(this.mountains.join('  '));
                }, delay);
            }
        };
        tahoe.print();