Ordinary copying is normal sketch.
Sketch copying is a simplified and enhanced version of ordinary copying. Pay more attention to structure and level. The main points are prominent. It is equivalent to an ordinary copy rack. Sketch requires the simplest and fastest speed to print the picture. Sketch, continue to draw, add some details, and it will be an ordinary sketch.
Sketch is a quick sketch technique in art. Just like when we are building, we need to design the outline of a building first, and sketch also means this.