Love - should I tell this guy I like him, even though he's older than me, Im 15?

First you have to ascertain the truth of your feelings, if you love him or this is just interest, if you ascertain of it, now tell him maybe he's having the same feeling, but if he not don't worry you're in the beginning of the life you will fall in love with a Guy and he for sure will love you, try why not!! :)
This is my suggestion :)