Sync Mode is the default UI that GitSync starts with.
Client Mode is an additional option, mostly for more advanced users, that changes the app UI to be more similar to that of a fully fledged git client. You can still access automated sync settings, but you will now have the options to fetch, pull, stage, commit & push changes separately.
Client Mode is still in a bit of a beta phase, which is why it isn’t adevertised for use at the moment. I appreciate your patience during this process!