What is the difference between a dot-density map and a choropleth map?

Dot Destiny maps show the geographic density distribution of a phenomenon by placing dots representing a certain quantity of the phenomenon where they are most likely to occur. 

And a Choropleth map show where areas are shaded according to a prearranged key, each shading or colour type representing a range of values. 

So Dot Destiny map uses dots, while chropleth uses Shades

Hope this helps

Dot maps use dots to represent a stated amount of some phenomenon within a political unit. Using a scale equating one dot with 1,000 people, 12 dots in one area would represent 12,000 people living in that area. On a choropleth map each political unit is fulled in with a distinguishing color or pattern but nstead use lines to join points of equal value across the mapped area. So in short, one map uses dots, and the other uses lines.