An economic system is comprised of the various processes of organizing and motivating labor, producing, distributing, and circulating of the fruits of human labor, including products and services, consumer goods, machines, tools, and other technology used as inputs to future production, and the infrastructure within and through which production, distribution, and circulation occurs.  These processes are overdetermined by the political, cultural, and environmental conditions within which they come to exist.  In comparative economic systems, these economic systems are usually defined within determinate political boundaries.  Thus, one would speak of a Chinese economic system, although China may, in fact, be a complex conglomeration and interaction of economic systems. Nevertheless, bounding economic systems in this way provides a way of discussing how such systems are made possible and changed by the specific effects of politico-institutional, cultural, and environmental differences.  Thus, one might discuss how the capitalist economic system of 1999 Germany is different from the capitalist economic system of 1999 Britain, for example.
 
Mainstream comparative economic systems was, for a long time, largely a propaganda tool used in the Cold War.  Thus, there was very little science employed.  Instead, the course was used to promote the NATO economies, primarily the United States and Great Britain, as the best possible economic systems and the CMEA economies, primarily the USSR, as the worst possible economic systems.  Systemic similarities between economies across this NATO/CMEA divide were ignored, as were careful definitions of economic, political, and cultural terms.  The possibility that Stalinism was compatible with a form of capitalism, for example, was never explored, despite numerous examples of totalitarian political systems wedded to relatively open (free-market) versions of capitalism.  More recent mainstream approaches to comparative economic systems are less polemical, focusing on the way non-economic factors influence (as exogenous variables) the structure and functioning of economies.
Respect for private property

in Islam

is considered an undeniable

certitude.
Private property ownership
is considered legitimate
in capital, land, cash,
and other things,
including
human beings.

---Nomani and Rahnema, Islamic Economic Systems