Thanks for your question. These terms are frequently used interchangeably, as a program frequently operates as an intervention. Though, these words do mean different things. A program can broadly be defined as an organized collection of activities, designed to meet certain objectives or goals. An intervention can broadly be defined as something that is created to intervene, perhaps to prevent an undesired outcome, or to promote a desired outcome. In reading the definitions I've provided here, we can see how and why these terms get used interchangeably. If in creating a program, our objectives or goals are to prevent an undesired outcome, our program is acting as a intervention. Interventions can extend beyond programs, though. If we use the definition I've provided here, many laws or policies can be considered interventions (e.g., the legal drinking age if thought to be implemented to prevent alcohol-related harms to young people), as could entire systems (e.g., the criminal justice system as an intervention to prevent or mitigate crime and its impact).
It's not surprising that in the book you're using, the word, "intervention" comes up quite frequently. While "interventions" are not limited to research settings, and "programs" are not limited to community settings, folks in academic/research communities may be more drawn to the term, "intervention," while communities like the word, "program." This may be because researchers are frequently interested in if a specific program/intervention is effective in intervening, while communities may feel as though the word, "intervention," feels too clinical.
I hope this helps, and that all goes well in teaching this course. Please do come back and visit with us if more questions come up for you.