Thank you for the opportunity to help you with your question!
The difference is that trafficking implies that people are being involuntarily taken somewhere usually for forced labor or sexual exploitation, while smuggling is voluntary. As an example, Mexicans who pay someone to take them across the border are being smuggled, not trafficked, while many people in prostitution are victims of trafficking in that they were brought from somewhere else involuntarily.
Please let me know if you need any clarification. I'm always happy to answer your questions.