Polar charts are similar to X-Y (Cartesian) charts, but they use polar coordinates. In this type of charts, the X axis is wrapped around the perimeter while the Y axis extends from the center to the top.
A radar chart is a useful way to display multivariate observations with an arbitrary number of variables. The radar chart is a chart that consists of a sequence of equiangular spokes, called radii, with each spoke representing one of the variables. The data length of a spoke is proportional to the magnitude of the variable for the data point about the maximum magnitude of the variable across all data points. A line is drawn connecting the data values for each spoke.
A filled radar chart is similar to a radar chart, with the difference that the area between the line and the center of the chart is filled.
A polar area chart is similar to a typical pie chart, except that sectors are equal angles. They differ in how far each sector extends from the center of the circle. The polar area chart is used to plot cyclic phenomena (e.g., count of deaths by month).