What is the difference between Chinese Mahjong and American Mahjong?

Chinese Mahjong (specifically the international standard, MCR) uses a points system called fans, where hands must meet a minimum fan threshold to win. American Mahjong uses a card published annually by the National Mah Jongg League with fixed hand patterns, joker tiles, and a very different scoring system. The tile sets, winning conditions, and overall gameplay feel quite different; Chinese Mahjong rewards flexible strategy while American Mahjong rewards memorizing and chasing specific card patterns.