economics:  study of the production, consumption, and distribution of commodities, defined in turn as those goods, services (including labor and capital services) and relationships that are explicitly traded for one another or for currency.

political economy:  study of the social and political institutions and conventions that underlie economic activity (e.g., the ownership of property, labor, and capital), and how these institutions and conventions determine the distribution of commodities among human societies.

geography:  (1) the distribution of physical, social, and human-built components across the earth’s surface;   (2) the study of these distributions, their determinants, and their relationships.
 
  “Economic geography is concerned with the spatial organization and distribution of economic activity, the use of the world’s resources, and the distribution and expansion of the world economy” [Stutz and de Souza 1998: 41].