Cutting plane lines are interpreted as actually slicing the object in two. The sliced object is then shown in a section view. The position of the observer is shown by the direction arrows.
Viewing plane lines are similar to section lines in that they indicate the point of view of the observer relative to a particular view. However, unlike section lines, viewing plane lines to not “cut” the part.
Some companies will choose to use different line types for section views and for cutting views. Be sure to conform to the standard you are working under.