What is the difference between / directory and /root director?

Question

In Ubuntu filesystem, there is a / directory which is called to be root directory and then again in that / directory there is a directory literally named root, what is the difference between them?

Answer 1

/ is the topmost directory in the file system.

/root is the home folder for the 'root' user (see id root).

All of those are sometimes confusingly designated by one word, root.