- The "main process" which manages the windows (renderer processes)

- The renderer process" contains the UI thread for each window, the renderer process can have its own worker threads

- The extension host loads extensions in proc, extensions are free to create their own threads/processes. The separate process for extensions protects extensions from freezing the renderer

- Various other processes that live off either the main process or the "shared process", such as the pty host for terminals which enables the terminal reconnection feature when reloading a window (also file watcher, search process)

We've been shuffling where processes are launched from recently but the actual processes and their purpose probably won't change. You can view a process tree via Help > Open Process Explorer to help understand this better.

EDIT: Formatting