(in cognitive science
) is a relation between higher- and lower-level features. Physically (lower-level) identical systems must be identical also mentally (at the higher level). According to the theory of supervenience a physical copy should have a mental counterpart.
Supervenience also implies that different systems must be physically different. It also mentions a dependency between lower- and higher-level features: lower-level features are primary and may exist without higher-level features. Higher-level features depend on lower-level ones and cannot exist without them.
See also Philosophy of mind and Functionalism