There are many differences between IB MYP and IGCSE. In a nutshell, IB MYP is a framework, IGCSE is a curriculum. In layman terms, IB MYP allows teachers to build a curriculum with guidelines; IGCSE is taught with straightforward teaching expecting specific outcomes (external examinations).
In general, IGCSE examinations have the so-called right answers or model answers. Students learn the concepts and are expected to produce the only answers; deviations from the answers will result in losing points. The good thing about it is that it is relatively easy to get good grades, the downside is that it limits the learning of the students and creates a big gap to reach to the next 2 years, whether it is A-Level, IBDP, or any other curricula.
IB MYP does not have any formal examinations. Students are assessed with a series of criteria in each of the subjects through a variety of activities; some could be written, some would be solo or group presentations. Depending on the dynamics between the teacher and students, learning can be expanded or restricted, nonetheless, the focus of the programme is to enable students to learn and practice the skills necessary to study the IBDP, not so much on the knowledge itself. We usually oversimplify such processes as learning to learn.
We ought to answer the question if the students/parents have a choice. For IB MYP students, IGCSE allows private candidates, in fact, many parents choose to register their children to a few of these exams to give them experience in public examinations. It also helps to gauge their learning in the knowledge of the specific subjects. Parents need to be aware that some of the topics tested in IGCSE may not be covered by the school’s syllabus. On the other hand, an IGCSE student can enrol to NTK Junior Academy course and learn the specific skills, such as critical and creative thinking in both English and Mathematics, which will be much required in the IBDP years.