Most systems are allopoietic systems. That is they produce something different from the system itself. A common example is a car. A car has many consituent parts that work together to produce a driving vehicle; no part of the system resembles a driveable vehicle however.

Compare this with autopoietic systems: systems that produce themselves. Living organisms are the most common example of an autopoietic system. Your body produces itself for example. Skin cells produce skin cells; people produce people.

See also the wikipedia definition of Allopoiesis.