At the start of a turn the striker's ball may roquet each of the other three balls once. In the International game you start each turn alive on everything, irrespective of what you did on any previous turn. There is no deadness board to keep track of. Within a turn you cannot roquet a ball a second time before scoring a hoop, but as soon as another turn comes along you are allowed to roquet all three balls again. An easy roquet is virtually never turned down.
International rules is definitely a much simpler game.
If you walk up to an International rules game and you can see the clips and position of the balls you know exactly what's happening, but in USCA rules you need to see the board as well. In American rules if the striker's ball hits a ball it is dead on, the shot is a fault and both balls are replaced to where they were when the shot began and the turn ends. There is no such rule in International. In International rules if the striker's ball hits another ball for a second time before scoring a new hoop it is not a fault, the striker's ball can go on and roquet another ball or score a hoop after the deflection and neither ball is ever replaced. In American rules when a ball sticks in hoop 1 the following player can attempt to play a half-jump shot.