Forum:Selective Tributing vs Normaling

So can anyone explain the difference between cards that state "This card can only be tribute summoned by...." and "This card can only be normal summoned by...." It just doesn't make sense to me why some cards state that they can only be tribute summoned in a way, or have an effect that says "When this card is tribute summoned..." and some cards say they need tributes to be normal summoned. Is it really the same thing, and if so, why would Konami word it so weirdly? Just wanted to know.