Nativism is one form of opposition to immigration. Strictly speaking, nativism distinguishes only between those who were born in a country (natives) and those who have immigrated. Thus, it ignores, for example, the race of individuals.
Many forms of opposition to immigration is not based on nativism, but instead on, for example, nationalism, but the term nativism has confusingly in, some countries, become a general term for 'opposition to immigration'.
Regarding immigration more generally and opposition to this, see the Migration article.