Rolling it like a cone just comes naturally. After youve been trying to roll like that for a while, it just happens all the time. Even when I roll a ciggy they come out looking like spliffs. I always add a roach, its just something to give it a bit of support and stop it bending in two (us brits dont like to get high - we get blitzed) so our joints are usually fat.
Ive got my own definitions. A spliff is thin and long, a joint is short and fat, and a bifta is fat, long and pure.