What is the difference between nationalism and imperialism?

Nationalism is the feeling of one's own nation state .it leads people to believe that their nation is better than others nation.It is a feeling of independent nation state While Imperialism is the condition where one country wants to extend its control over other countries(increase the border).

Compare the different ways in which the Belgium and Sri Lanka have dealt with the problem of cultural diversity

Belgium amended many times their constitution to promote equality and unity. There were equal number of ministers of both the groups in the council. it also promoted community government. On contrary Sri Lanka adopted majoritarianism policy.