straightedge is used only to make or draw a straight line but not to measure the length as it does not have measurement gradients. A ruler has two parallel lines or edges which have centimeters and millimeters on one side and inches on the other. straight edge is a cutting guide tool for copying a straight line from one location to another or checking the straightness of a line already drawn. A straight edge with equally spaced markings on it is called a ruler
A straightedge is used only to make or draw a straight line but not to measure the length as it does not have measurement gradients. A ruler has two parallel lines or edges which have centimeters and millimeters on one side and inches on the other.
