Core Activities: Core Activities are central and crucial to the basic business purpose. For example, the purpose of a school is to develop a child by means of curricular and co-curricular activities. So, these activities are core activities for a school.
Non-Core Activities: Non-Core Activities are activities other than the core activities. These activities are regarded as secondary or incidental to fulfilling the basic purpose. For example, running a cafetaria is a non-core activity for a school.