Is an inventor the same as a founder?

No.

An inventor is someone who comes up with something entirely new, while a founder is(usually) someone who starts a new organization.

Let's use schools and libraries as an example, they've been around for quite a while, so you can't claim to invent one. But if you put the money in, you can be the founder of one.

Invention is a measuring tool, usually created from the pursuit of new knowledge. It is a proof of concept.