That is not what I meant. I was not comparing the two. I know that I can create a similar image without shadows in the Viewport Display (View > Rendered) as in the second posted image one by changing the Viewport background to white (Rhinoceros > Preferences > Colors > Viewport colors > Viewport background), and by removing the display of the grid lines, grid axes and world axes icon ( File > Settings > Grid)
However that was not what I was after. I wanted to Render > Render, since for that I can also choose the level of Antialiasing.
I did not know this. I was looking in “Viewport settings”, where “Shadows” is greyed out. And as I mentioned I had gone to Render Settings > Advanced, where there is a section called “Preventing self shadowing”. Changing the value there does not seem to affect anything.
This I know. I was looking in the wrong place to turn “Cast shadows” off.
Now I have a new question. What is this “Preventing self shadowing” setting for? What does changing the value do?