Why they feel so different
In Chinese mahjong you build toward a shape (four sets and a pair) and score what you made. In American mahjong you build toward one exact hand from the card and switch when the tiles don't come. The card is new each year, so even long-time players relearn it every spring.
The tile counts, worked
Both use 108 suit tiles, 16 winds and 12 dragons: 136. A Chinese set adds 8 flowers and seasons for 144. An American set adds 8 flowers and 8 jokers for 152.
Japanese mahjong
Riichi, the Japanese game, is closer to Chinese play: 136 tiles, no jokers, no card. Its rules don't carry over to American mahjong either.
Questions
Can I use a Chinese mahjong set for American mahjong?
Only with 8 jokers added, and racks help. Some sets also lack the flowers American hands need.
Is American mahjong harder than Chinese?
Different more than harder. American mahjong has fewer choices each turn but a new card to learn every year.
Why does American mahjong have a card?
The National Mah Jongg League publishes the list of winning hands each year; only those hands win.
Do American players call chows?
No. You can't call a tile to finish a run; calls are for groups of identical tiles, or to win.
Related cards
Small Table Mahj is an independent guide written in our own words. It is not affiliated with or endorsed by the National Mah Jongg League, and it shows no hands from the League's card. Buy this year's card from the League.