It depends on the region. In the southern regions, 米饭 means uncooked rice, a general term as in "grains". 白饭 means cooked steamed rice. You don't say 吃米 because it is not edible until cooked. In northern regions, they both mean the same. However, we all can understand what you mean given the context. As in English, depending on where you are, the word "rice" takes the correct meaning. You won't get a boxful of uncooked rice grains from a Chinese restaurant. for a takeout. 白米 and 白飯 are two entirely different things since unpolished rice is not white.

In our daily life, we don't distinguish them. In the north of China, we often use 米饭.

米饭 and 白饭 这个算是有地方习俗的一种称呼，广义上他们是一样的，建议如果你想说rice，你就说米饭

not really

Yes. There is. "米饭" means rice. Never heard of "白饭".