Immigrants take an active part in the society, they got to school, get a job and speak the language. Integration does not mean you have to give up your culture.
Assimilation means that immigrants must adapt as much as possible and encouraged to adapt the national culture. Assimilation is the process whereby a minority group increasingly adapts to the customs and attitudes of the prevailing culture and customs.
The word segregation means separation.
Segregation happens in two ways:
1 - spatial segregation: groups have their own area to live in. Examples; rich/poor, ethnic neighbourhoods (Little Italy, Chinatown).
2 - social segregation: groups live separately from each other. Examples; groups have their own schools, own sports clubs. The groups have little or no contact with each other.