If every piece of a ship is replaced, is it still the same ship?

Replace a ship’s wooden planks one by one until every piece is new. It keeps sailing under the same name.

Now build another ship from all the old planks. Which one is the original?

One has kept going through the years. The other has the original wood. This puzzle, called the Ship of Theseus, asks what makes something the same thing: an unbroken history, or the same parts?