Difference in screen resolution in Remote connections between RealVNC & Windows Remote Desktop
Solution 1:
1) VNC and RDP are two very different protocols despite being used for similar purposes.
With VNC, the remote system is basically sending you the pre-rendered output of the remote system's video card at whatever resolution it is currently running at. With RDP, the remote system is simply sending over logical information about what needs to be drawn on the screen. Your system then renders that information using the local video card at whatever resolution your RDP client has connected with.
2) Depending on your VNC client, there might be options to shrink the remote display so it fits in your current resolution. Your other option is to actually change the remote system's resolution to match your local resolution for the duration of your connection.