A state = a nation, country or territory that has an organised political community by one government and which no other state has any power or sovereignty over - in other words, a self-governing nation
A nation is a territory of people that may or may not have sovereignty
E.g. Wales and Scotland are nations which are part of the UK
The UK is a sovereign state, but Wales and Scotland, whilst devolved from the UK government, do not hold full autonomy and cannot therefore, be considered independent sovereign states
A sovereign state has:
The highest authority over its territory
A permanent population
Defined territorial boundaries
A government not ruled by another - is independent
The ability to interact with other sovereign states
A sovereign state can exist without being recognised by other sovereign states, although unrecognised states find it hard to make treaties with other powers or have diplomatic discussion with other sovereign states - Taiwan is not recognised by China
National sovereign states vary greatly in their ethnic, cultural and linguistic unity due to the:
History of its population growth
Degree of isolation
Role of migration
Many sovereign states will have an identity (e.g. American, Italian etc.) but it will have come from different cultural backgrounds over time:
For example, the USA, before colonisation, was home to a mix of indigenous peoples/tribes
With in-migration, the current population of the USA are the descendants of a 'global mix' of nations (Greeks, Italians, Spanish, Scots, Irish etc.)
From this mix, an 'American culture' has arisen, which is both inclusive and dynamic
Other states have kept relatively homogenous (single) cultural traits because;
They are physically isolated - Iceland's location has limited migration
They are politically isolated - North Korean policies limit interaction with foreign nations
Nation states can therefore, be considered an agglomeration of many different peoples living in one united territorial area