Hi, thomasallenpdt0!
Push factors: A negative aspect that motivates one to leave; in migration, push factors are those that encourage a population to leave it's home.
Pull factors: The advantages a country has that make a person or population come live there.
Forced migration: A general term that refers to the movements of refugees and internally displaced people as well as people displaced by natural disasters, chemical disasters, famine, or development projects.
Voluntary migration: Migration based on one's free will and initiative; volunteering to migrate.
Hope I helped you! :)
~Olivia