what is the differences between a state and a nation and a state-nation
There are three different things to define here: 1  State: A state is an organized community living under a unified political system, the government (Wiki definition). 2  Nation: A nation may refer to a community of people who share a common language, culture, ethnicity, descent, or history (Wiki).
The idea of a nation and a state being the same thing (Nation-state) is fairly new in modern politics [1] (it came about as one of the consequences/results of Peace of Westphalia, which ended the 30-year-war in Europe, when the concept of Westphalian sovereignty was introduced).