In connection with Purim, the Talmud says, "A person is obligated to drink until he doesn't know the difference between 'Cursed be Haman' and 'Blessed be Mordechai'." On Pesach, the four cups of wine represent the four expressions of redemption which the Torah uses, namely "I took you out", "I saved you", "I redeemed you" and "I took you for Myself as a People." On Purim, drinking of wine is used in conjunction with the idea of "hester panim," of masquerade, of changing the identity, of confusion and forgetting. On Pesach, wine is used to bring into sharp focus the different aspects and nuances of redemption, so that we can fulfill the commandment to tell the story of our Exodus from Egypt to our children and grand-children.
On Purim, wine is drunk to help us forget the terrible experiences of the Exile; the pogroms, the massacres, the concentration camps - the flight and the terror. On Pesach, wine is drunk to raise us to an exalted level, "And wine gladdens the heart of Man," so that we can remember the glorious experiences of our past: We re-visit our Avos, experience the triumphant redemption from Egypt, are present at the Revelation and Receiving of the Torah at Sinai, experience the beauty of Jerusalem and the Temple in the time of Shlomo, share the faith of Rabbi Akiva and the greatness of our Torah sages throughout the generations. In the family setting of the Seder, it helps us recall transcendent Sedarim of our childhood. We are present at the establishment of the State of Israel in our time. And we have vividly in our mind's eye the restoration of the Temple at the time of the Mashiach. It helps us blend our praise and prayers for past, present and future redemptions.
To forget and to remember are both great gifts of Hashem. Forgetting enables us to come to terms with our own mortality and that of our loved ones. And remembering helps sharpen our self-identity and identification with our People.