What is the difference between resilience and adaptation?

Adaptation describes the ability of a system, and more specifically of a process or function of that system, to adjust itself to external conditions, usually expressed by the value of one or more variables. Adaptation is therefore basically reactive. The adjustment serves the purpose of maintaining an equilibrium state between the system and the environment, as defined by the desired values of the variables.

Resilience describes the ability of a system to adjust its functioning, prior to or following changes and disturbances, so that it can sustain operations even after a major mishap or in the presence of continuous stress. Resilience is therefore both reactive and proactive. Being proactive allows the system to change before the environment changes, thereby being able to meet or counter the conditions that are expected to arise. The overall objective is to sustain functioning in the long run, even if it involves changed ways of operating (e.g., through reconfiguration), and even if it involves a transition to a different equilibrium state.