I don’t know much about the tech behind either, but when I’m using VNC it feels like I’m just remote controlling the mouse and keyboard on another machine via a series of streaming jpegs and when it’s full screen I either have to scale the display so all the elements on the screen are too small or too big, or have scroll bars.
With RDP it’s so smooth it’s like I’m on the other machine. RDP doesn’t just remote control the screen on the other computer, it creates a new desktop session formatted for the remote computer. Someone else can even use the other computer while you log in as a different user. I don’t know if VNC can do this but RDP can even forward local drives and devices to the remote computer, you could plug a USB into your laptop and have it connect to the machine you’re RDPing into. It’s so seamless that I often forget I’m using a different machine when I have it in full screen.