New Project, Open Project, Reload Project
The New Project command 
creates a new project. The new project replaces the previous project (if any) in the Projects sidebar. If the project you have been working on has unsaved changes, a prompt appears asking whether you wish to save changes to the project. Note that the New Project command only creates a new project without saving it; you have to explicitly save the project using the Save Project command.
The Open Project command 
opens an existing project and displays it in the Projects sidebar. If a project was previously open in the Projects sidebar, it is replaced by the opened project. If the previous project has unsaved changes, a prompt appears asking whether you wish to save changes to that project before it is replaced in the Projects sidebar.
The Reload Project command 
reloads the current project. This command is especially useful if you are working in a multi-user environment, where other users might make changes to the project.