Honors and seminar English classes are both rigorous, and they both expect students to be at the same level of advancement.  The biggest difference between the classes is discussion.  If your student is in seminar, a significant percentage of his or her grade will be based on how prepared he or she is for discussions and his or her participation level in discussions.  If your student is extroverted and enjoys debate, seminar is the right choice.  Honors covers the same material, but discussion has far less of an impact on your grade.  If your student is introverted, this class will be a better fit.   Both seminar and honors prepare students for AP.