Are Haitian migrants being deported, repatriated or expelled? And what's the difference?

The plight of thousands of Haitian refugees awaiting asylum at the U.S.-Mexico border in Del Rio, Texas captured national attention Sunday when video showed U.S. Customs and Border Protection agents chasing the migrants on horseback.

Homeland Security Secretary Alejandro Mayorkas told reporters Monday that CBP is coordinating with Immigration and Customs Enforcement and the U.S. Coast Guard to move migrants to other processing locations for removal.

DHS officials said Thursday about 7,000 migrants remain in Del Rio, Texas — less than half of a peak of about 15,000 on Sept. 18.

The migrants have been moved to other sectors for processing. Some have been expelled back to Haiti or Mexico.

What justifies an expulsion? And how does it differ from deportation or repatriation? Here's an outline of the terms:

Some migrants face immediate expulsion

Migrants encountered by U.S. Border Patrol and the CBP Office of Field Operations (OFO) can be expelled to their home country or country of last transit for various reasons.

Some Haitian migrants in Del Rio have been immediately expelled to Mexico under Title 42, a Trump-era public health policy allowing CBP officials to turn away undocumented migrants to subdue the spread of COVID-19. The Centers for Disease Control and Prevention extended the policy indefinitely in August.

Migrants who cannot be expelled to Mexico are detained for the shortest time possible while CBP collaborates with interagency partners to expel the individuals to Haiti, according to the agency's official website.

Children and some families are exempt from Title 42.

Deportation involves removal from the country

Deportation is the formal removal of a foreign national from the U.S. for violating an immigration law, such as committing a criminal act or threatening the public safety of others.

In some circumstances, a foreign national may be held in a detention center to await deportation or a trial. Those who come into the country with forged documents may be deported without a hearing under an order of expedited removal.

Haitian migrants repatriated under U.S. policy

Repatriation involves citizens returning from a foreign country to the country of origin.

Since Sunday, DHS has conducted 12 repatriation flights to expel more 1,400 Haitian nationals to Haiti, according to the El Paso Times.

Daniel Foote, Biden's special envoy to Haiti, resigned Thursday over the repatriation policy.

Reach out to Chelsey Cox on Twitter at @therealco.

This article originally appeared on USA TODAY: Deportation, expulsion, repatriation: What's the difference?