unexpected output using this keyword

Question

When I use an anonymous function to get value from a function it gives me undefined.

let objectStudent = {
    name : "Muhammad Abdullah",
    age : 21,
    rollNo : "FA20-BCS-084",
    Degree : "Computer Science",

    compareTo : () => {
        console.log(this.name);
    }
}
objectStudent.compareTo()

output : undefined

But when I use it using function keyword, it gives correct output

 compareTo : function(){
        console.log(this.name);
    }

output now : Muhammad Abdullah

why is this happening?