I think that originally, in ancient vampire lore, the stake had to be a specific type of wood, and it was only a part of the process, but Hollywood simplified it. If I recall properly, in Stoker's "Dracula," the Count was beheaded, his mouth filled with garlic, and a wooden stake was driven through his body into the soil below in order to keep it from ever rising again, though what harm a headless vampire could cause is beyond me. In "The House Of Frankenstein," simply removing the stake from Dracula's corpse would allow him to rise again. These days, anything from a pencil to a fence post will do the job permanently, assuming that it's real wood of any kind, and it penetrates the heart.
I guess they just don't make vampires like they used to.