How there is difference between currency value? Who/What factors decides that?

Answer 1

Currency values are determined by how much production and actual stuff is available for purchase. Since individuals rarely want the money itself but instead want what it will buy, it is a case of supply and demand. I think what you are asking is why there is a difference between different countries currency. It depends on how much of the currency is in existence, and how much that particular country exports and imports. The more exports they have, the higher demand is for their currency, and thus the higher currency value.