Differences between using Lambda Expresions and without using it? : Could someone explain my the differences between methods using lambda expresions and without using it ? 
On the example :

     Function<Double, Double> function;

    public void methodCounting() {
            this.function = x -> x = x + 2;
    }  

     public void methodCounting(double x) {
                 x = x + 2;
                return x;
        }  

What do we gain ? 