What is the difference between expiation (kaffarah) and making up missed days (qadaa') in the rulings of fasting, especially when masturbating, which invalidates the fast and necessitates making up that day—and is making up the day sufficient?

Qada' (making up) is fasting a day for each day a person missed. As for Kaffara (expiation), it is obligatory for whoever nullified their fast by sexual intercourse during the daytime in Ramadan, and it is: freeing a slave; if one cannot find one, then fasting for two consecutive months; if one is unable to do that, then feeding sixty poor people. Kaffara is not obligatory for whoever nullified their fast by masturbation; they only have to make up the fast (qada').