Hi Clay, basically, all the difference is between the groups is the run time. Group A runs first (usually about about 8:30 or 9 am), and then Group B, then C, then D is the last group out, usually at about 11:30 or noon. Anyone is allowed in any group. You usually complete your work assignment 2 groups before or after your group, i.e. A works for C, B works for D and vice versa.