Mac OSX Screen Sharing: Does the remote screen display my actions?

During my work-from-home days, I use a Mac Mini at home to access my Mac workstation in my office through a VPN set up by my IT department at work. When I use OSX's Screen Sharing at home to control my workstation, does my workstation in my office display what I'm seeing & doing on the screen share at home, or is the screen still blank? If someone is in my office, can they see what I'm doing?

Yes, it does.

Apple Screen Sharing is just a VNC server, and you can connect to it with any VNC client. Anything you do in the VNC client window i.e. your work computer screen will be visible on the workplace monitor. Anything you do outside the VNC client window you're doing on your own system, and is not reflected in the remote end.

Just to be clear - I don't have 2 Macs to test with, but I connected to my MacBook from my Linux box using a standard VNC client. I don't know whether the client screen is reflected on the server side as well. I doubt it, but cannot confirm.

As advised by Tetsujin, the way to overcome this is Apple Remote Desktop. It contains a curtain mode, which blocks or conceals the display on the computer Screens is connected to, i.e. the remote screen won't show what the user's doing. Note that this is a paid product.