Why doesn't text fit in rectangle drawn

Question

I created a rectangle using Zelle graphics.py and wrote text of 10 points into many lines down the long narrow rectangle. Words fit from the left to right side of the narrow rectangle.

Now I moved the python code from my Windows 7 PC to my Windows 7 laptop. When I ran the program, the letters were overlapping the boarder of the rectangle. I had to dop the point size from 10 to 8 for it to look the same way as on the PC.

This does not seem to make sense since the pixel size of the overall window has not changed. It is the same code and it is the same version of Python on both systems.

The overall windows size appears smaller on the laptop than the PC. I assume the pixel density is different between the two computers. But I would not expect the text appear differently on the two machines. Yet the text fits in the box on one but not the other.