In addition to offering foreign language and home country language classes, a bilingual school may teach Mathematics and Science in the home country language and Social Studies in a foreign language. Bilingual schools tend to cater to students from the local community so they have less diversity in their student bodies. Some international schools are also becoming less diverse as they try to cater to the local community.
Although international schools can be similar, each school is unique. For example, some international schools offer a British style of education and others an American style. Some bilingual schools are nonprofit while others are for-profit. And some schools are day schools and others offer boarding.
Each school chooses to focus on what it believes creates temporary and/or sustainable competitive advantage in the market they serve.