This research aimed to compare physics syllabi on the diffraction concept implemented in Indonesian, Malaysian, and International schools. This research used a qualitative approach with document analysis and interview methods. The analysis showed that the syllabi used in the three schools exhibit significant differences even though both neighboring countries use similar instructional languages. The differences are highlighted in concept usage terms, students’ ages, and the concept delivery flow. The interview findings showed that the teachers developed their teaching and learning activities based on the students’ circumstances and the availability of teaching aids and practicum instruments.