Currency devaluation is the fall in the value of one currency in terms of another currency by the decision of the central bank. Currency revaluation is the rise in the value of one currency in terms of another currency by the decision of the central bank. On the other hand, currency depreciation is the fall in the value of one currency in terms of another currency in the flexible exchange rate system. Currency appreciation is the rise in the value of one currency in terms of another currency in the flexible exchange rate system.