Difference between Idli Batter and Dosa Batter

What is the difference between Dosa Batter and Idli Batter
The proportion of rice and urad dal is generally 2:1 for idlis and dosas. I have myself made both idlis and dosas using this proportion and they have come out well at all times. But to make the dosas crispier, you could use 3:1 proportion of rice and dal respectively.Generally, the Dosa batter is thinner than than the Idli batter. This consistency is required to make the crepe or thin pancakes.The Dosa is crusty and crisp, while the Idlis are soft and fluffy. Yet I have had soft dosas and they too are good. One can just add water and thin the Idli batter to make crispy Dosas. You could also add some ground chana dal to the batter to make crispy dosas.
You could also Dahi, (Curd, Yoghurt) to the idli batter. The lactic acid and the butter-fat in the curd or yoghurt, tenderizes the batter, making the idlis soft.