nation = country?

[Eway]

Is the concept of a "nation" exactly the same as a "country"?
Take U.K. for example,
it seems England, Scotland, Walse and Northern Ireland are all viewed as "a country" respectively.
Does this mean:
England = a country
Scotland = a country
Walse = a country
Northern Ireland = a country
England + Scotland + Walse + Northern Ireland = a nation
??

[Tdol]

Nation is more used when we are thinking of the bonds that unite the people, rather than the geographical and political entity. Also, some people that have an identity but do not have a geographical country can be referred to as a nation.