There are no differences. Classes are offered in different time slots for convenience. However, if you want to retake grammar class, take French IA/IB (grammar). If you want to retake practical training class, take Primary French A/B (seminar). In AY2016, French classes in primary level were rearranged as two-credit courses. But if students who entered in or before AY2015 register this rearranged course and earn credits, only half of the credits is approved as credit required for graduation. Also note that you cannot carry credit earned in IA class to IB class, and vice versa.