What is the difference between “migrant” and “immigrant”?

In the context of the Migrant Education Program, the term "migrant" refers to an individual who, within the past 36 months, has moved across school district boundaries with the intent to obtain seasonal or temporary employment in agriculture, fishing, and dairy of food processing work. "Immigrant" refers to a person who has entered the United States from another country. Not all migrant farm workers are immigrants, and not all immigrants are farm workers.