Meat from the animals back is always more tender than meat from the shoulder and limbs. This is because the back muscles are not used as much, so they have less collagenous tissue attatched to them. Filet mignon is the most tender steak, though ribeye, while less tender, has more flavour. Porterhouse is also good for taste as it has a good amount of marbling.
Fillet steak works pretty well for grilling. Then you can also barbeque fish (you wrap it in aliminium foil before grilling it). It tastes delicious.
Overhere we just ask for a fillet steak. But yes, as far as I know they are the same.
So if I'm correct its a ribeye cut?
Do you mean fillet mignon?