Isopleth and Isometric maps display two different types of data.
– Isometric maps show lines of points with true data, meaning that data at that point is accurate (along the line of a topographical map labeled 500 feet, the points that make up that line are all 500 feet in elevation).
– Isopleth maps, however, show lines of areal data (not point data like isometric), and therefore the lines approximate phenomenon. Along the isolines, however, the values do not equal exactly what the lines project.