Even though Eoghan is only 16, hes not gonna wake up one day and say, sound like Elton John. He is stuck with his sorta light boyband-ish voice forever. Of course with age it's going to get abit stronger and on a technical level, better.
Mali was only 15 but his voice had so much power and gravel to it. You can tell when he is older and gets full control over his voice, he is going to be amazing. Where as sadly I don't think Eoghan will ever go beyond sounding average. I don't think he is solo artist material and really not good enough for the final 12. Put him in a group and then he will be ok but I think he is probably the weakest (vocal wise) male to make it through to the live shows ever.