The learning characteristics of each student are different. Differentiated instruction considers individual differences, as such guides the learning journey rather than seeing these differences as a challenge. The purpose of this research was to compare the effects of differentiated instruction and 5E learning cycle in physics classes on the students' academic achievement and self-efficacy. We used the matching -- pre-test/post-test -- control group design to address the research questions. We conducted the study in three different schools, performed three experiments, and had three control groups. 162 10th grade students participated in the study. We used the "Electricity Prior Knowledge Test," "Electricity Achievement Test," and the "Physics Self-Efficacy Scale" to collect data. SPSS version 20 software was used to analyze the obtained quantitative data. Independent samples t-test was used to determine whether there was a significant difference between the control and experimental group students' level of prior knowledge regarding the subject of electricity. The analysis of covariance was used to determine whether there was a significant difference between the control and experimental group students' course achievements after the implementation. Two-factor mixed-measures ANOVA was used to determine whether the experimental and control group students' pre-test and post-test scores on self-efficacy differed. Based on the results, it can be concluded that differentiated instruction improved the academic achievement of the low- and mid-achieving students. When the self-efficacy scores of the students were analyzed, no significant difference was found between the groups. Based on the results of the research, researchers or teachers who want to use differentiated teaching in their classrooms may be recommended to create level groups in the classroom.