All programs are different but being that your son is a junior, I would go with Prospect Camp. They are usually limited in players and instruction is given by the coaches, not others who come in to help run camps. Limit the Prospect Camp to your sons position. For example if he is a pitcher, go with Pitchers prospect camp. Just the word prospect doesn't really describe the type of camp.
It should be a camp from a program that your son is interested in. Coaches like players who attend prospect camps who are interested in their program.
I would suggest calling to find out if prospect camps are limited and instruction given by which coach.
Usually the assistant volunteers set up camp and easier to reach, but do it now if he is interested.