To understand the differences among charts, you have to distinguish between dimensions in space and dimensions of data. The two dimensions are distinct. Space can be represented as three dimensions along the x, y, and z axes. Corresponding to the X, Y and Z axes in the Chart Area. Data can either be represented in a two-dimensional or a three-dimensional (2-D or 3-D) space. In two dimensions, data is represented along the x axis and y-axis only, In three dimensions, data is projected back along the z axis also. Two dimensions of data must be represented in 2‑D space. At least three dimensions of data are necessary to use the third spatial dimension Stack, Cluster or Depth (z axis). But three or more dimensions of data can be represented in 2‑D space. For example, cluster and stack represent data categories in two spatial dimensions (X axis and Y axis only).