Question

What is the difference between PENUP
and PENERASE primitives?​

Answer 1

Answer:

pen-up 1.0 pu 1.0 pen-down pen-erase pen-up. The turtle changes modes between drawing lines, removing lines or neither. The lines will always be displayed on top of the patches and below the turtles. To change the color of the pen set the color of the turtle using set color.

Answer 2

The setpensize command decides the drawing pen size. penup or pu means pick pen up, so you can move turtle without leaving tracks.

PENERASE turns the turtle's pen into an eraser. When the turtle moves, it appears to erase by drawing in the current background color. To stop PENERASE, use PENDOWN, PENUP or SETPEN. Example.