ID overlap between posts & pages?

Hi. I’m studying how queries work in WordPress, and right now I’m testing the get_post( $id ) function. It seems to fetch the post by ID regardless of whether its a page type or a post type. I just want to be sure and couldn’t find the answer to this question: is the ID for every post – be it a blogpost, page, attachment, revision, custom post – unique? As in, a blog post ID will never be the same as a page ID?