Are there any differences between a repository and a working tree?
These two definitions tell us that a working tree and a repository are projects' files.
It is the repository definition in Github:
A repository contains all of your project's files and each file's revision history. You can discuss and manage your project's work within the repository.
It is the working tree definition in "craftquest" website:
The Working Tree in Git is a directory (and its files and subdirectories) on your file system that is associated with a repository.
They are totally different things.
The repository is invisible. It is where Git stores history.
The working tree is visible. It is where you create history.
From my https://www.biteinteractive.com/picturing-git-conceptions-and-misconceptions/:
I like to say that there are actually three worlds of Git:
The repository. I’m imagining the repository here as consisting (primarily) of stored commits. These are snapshots reflecting past versions of your work.
The index. This is where you configure what you want to go into the next commit.
The working tree. These are files that Git lends you from the repository, so that you can edit them and then add them to the index, in order to tell Git what the index (and hence the next commit) should look like. The working tree is the only part of this triad that you can see directly.