They're pretty comparable. A "clone" can almost always be considered a subset of a "rewrite". Both involve a new software system that is directly inspired by an existing one.
The main difference is that a clone is often written by developers who had no involvement with the development of the original system. But that's not always true, especially for any old or sizable software system, where the original developers may no longer be involved.
The main difference is that a clone is often written by developers who had no involvement with the development of the original system. But that's not always true, especially for any old or sizable software system, where the original developers may no longer be involved.