array.map(arrow function) is not same as a function with return value?

Question

I am learning Arrow Functions in Javascript. Impressed by the "Shorter functions" example or definition of arrow functions given on Mozilla's MDN page.

According to the page/example-

var a2 = a.map(function(s){ return s.length });

and

var a3 = a.map( s => s.length );

do the same job! and a2 & a3 store an array of lengths of strings of a.

So, I took up an initiative to compare the two(a2 and a3) and ended up getting the result as false (control goes to the else clause).

Here is my code-

var a = [
          "Helium",
          "Argon",
          "Neon",
          "Xenon",
          "Krypton",
          "Radon"
        ];

var a2 = a.map(function(s){ return s.length });

var a3 = a.map( s => s.length );

if (a2 == a3)
{
    console.log("equal");
}
else
{
    console.log(a2+" unequal "+a3);
}

I am getting this as the output in the console-

Even though a2 is the same as a3, why am I getting a falsified answer?