Is it a boat or a ship?

Again I'm confused. When is a boat a boat and a ship a ship? I know size matters, but as I am the way I am, I'd like to have an exact answer.

Let's say I have a friend whose neighbor is quite an irritating superlative type. You all know that type.

If my friend had it hard as a child, the neighbor had it harder. If my friend has an excellent job and quite a nice amount of savings, the neighbor has just a superb job, lovable boss and double the savings my friend has. If my friend is sick, the neighbors whole family is much more sicker. Almost like Ebola, but miraculously they all survive. And if my friend buys a boat, the neighbor surely buys a bigger one. Just enough that the neighbor can brag how they didn't bother to get a pathetic boat, but a fine and dandy ship. So my friend tells me.

So let me ask again. What is the size difference between a boat and a ship? 24 meters? If my friend buys a 23,5 meter boat and my friends neighbor buys exactly the same kind of a boat, and I mean literally exactly the same, but 24,5 meters long, is then my friends ship called a boat and my friends neighbors boat called a ship?

And don't you come here telling me the difference between a ship and a boat depends on a number of factors, because in this scenario there are no other factors. So give me a number.

Give
Me
An
Excact
Number

P.S.
I really, really, really wanted to put the horizon in the middle in these boat pictures.