Following the death of 10 people in San Antonio who died in a hot truck, some have used the terms human smuggling and human trafficking interchangeably.

Both are investigated by Immigration and Customs Enforcement, and the agency says the two terms are not interchangeable.

Human trafficking centers on exploitation. It’s better known as a crime against a person.

Someone is forced into labor, services or sex services by force, fraud or coercion. There is usually no choice to get out of the situation.

With human smuggling -- there usually is.

Human smuggling is bringing people into a country by deliberately evading that country's immigration laws.

It also includes hiding undocumented immigrants in the US.

Human smuggling can often to lead to human trafficking.

"You could take a smuggling situation that, just as you expected, arrive in the country, and then be trafficked at that point on,” said Melissa Torres, director of the Human Trafficking Research Portfolio at the University of Texas. “When the smuggling situation turns into a trafficking situation – that may or may not have had anything to do with the smugglers."

If you suspect human smuggling -- call the Immigration and Customs Enforcement hotline at 1-866-DHS-2-ICE or police.

A victim of human trafficking can call the Refugee Services of Texas at 1-888-373-7888.

Below is a timeline of U.S. Customs and Border Protection interceptions of immigrants in 18-wheelers.

MOBILE USERS: Click here to view the timeline