So Sasuke has one move he's used for three things. And? That still makes your argument ridiculous. "Rasengan and Rasengan Shuriken are the same because they both kill the oponent"
Other than the fact that power and the actual form in which the damage is dealt are different, what you say is fucking stupid. By your logic, mangaka should just all simply copy paste Kame-Hame-Ha indefinitely because no matter if the attack rips people to shreds, electrocutes them, burns them, twists their bodies, stabs them, detonates a nuclear bomb on them, erases their existence, etc, etc, etc, the end result will be "killing the oponent", thus making any difference meaningless.