The Hebrew Immigrant Aid Society (HIAS) offers the following definitions of refugee, asylum seeker, internally displaced person and migrant.
"Refugee: A refugee is a person who has been forced to flee their home country due to persecution because of their race, religion, nationality, political opinion or membership in a particular social group (e.g., members of the LGBTQ community). The persecution a refugee experiences may include harassment, threats, abduction or torture. A refugee is often afforded some sort of legal protection, either by their host country’s government, the United Nations High Commissioner for Refugees (UNHCR) or both. In the United States, refugees are hand-selected by the U.S. government and are screened in advance. They are subject to background checks and security screenings by multiple U.S. agencies. Only after everything is approved are they brought to the U.S. to reside permanently.
Asylum seeker: An asylum seeker is a person who has fled persecution in their home country and is seeking safe haven in a different country, but has not yet received any legal recognition or status. In several countries, including the U.S., asylum seekers are sometimes detained while waiting for their case to be heard.
Internally displaced person: An internally displaced person, or IDP, is a person who fled their home but has not crossed an international border to find sanctuary. Even if they fled for reasons similar to those driving refugees (armed conflict, generalized violence, human rights violations), IDPs legally remain under the protection of their own government – even though that government might be the cause of their flight.
Migrant: A migrant is a person who chooses to move from their home for any variety of reasons, but not necessarily because of a direct threat of persecution or death. Migrant is an umbrella category that can include refugees but can also include people moving to improve their lives by finding work or education, those seeking family reunion and others."
It is interesting to consider whether and how these concepts might apply to our interpretation of US colonial history. The National Park Service's "Historic Jamestowne" exhibit compares and contrasts Jamestown and Plymouth along several dimensions, including "Reasons for the colonies":
"Economic motives prompted colonization in Virginia. The Virginia Company of London, organized in 1606, sponsored the Virginia Colony. Organizers of the company wanted to expand English trade and obtain a wider market for English manufactured goods. They naturally hoped for financial profit from their investment in shares of company stock.
Freedom from religious persecution motivated the Pilgrims to leave England and settle in Holland, where there was more religious freedom. However, after a number of years the Pilgrims felt that their children were being corrupted by the liberal Dutch lifestyle and were losing their English heritage. News of the English Colony in Virginia motivated them to leave Holland and settle in the New World."
Were Jamestown's colonizers migrants? and Plymouth's refugees?