Are trimesters and semesters similar, or different? Trimesters and semesters are both alike and different, but they are still both good ways for a student 's education. They have many differences, and many similarities, when it comes to a high school students education. Trimesters are split into three different periods. Semesters are four quarters split into two periods. They both give students the same credit requirements and the same credits. Semesters differ from trimesters in many ways. Semesters give students seven classes a day throughout the whole school year. Trimesters give students five classes during the school period. The class time in semesters are only fifty-five minutes. Although, the class time for semesters are seventy minutes