Complex sentence: B1 visa is mainly used by people who go travelling to other countries in order to attend business meetings and trainings, whereas B2 visas are for the purpose of social visits, or visiting visas.
Split into simpler sentences: B1 visa is mainly used for business purpose where they go traveling to other countries in order to attend business meetings and trainings. Where as B2 visas are for the purpose of personal visit or visiting visas.