Rummy and Poker have always gone hand in hand. Both games are played in social setting, and both games have many international gaming communities. Since the games have become a part of everyday life, both rummy and poker have become a source of income (or loss) for many players all over the world.
Although the games have many similarities, the main difference is that in rummy, the skill element plays a bigger factor in the game than the element of luck.
This is the reason that rummy games are legitimate all over the world, even when legal jurisdictions ban gambling.