Type I Enrichment Activities are designed to expose learners to a wide variety of disciplines, topics, occupations, hobbies, persons, places, and events that would not ordinarily be covered in the regular curriculum.
Type II Enrichment Activities promote the development of thinking and feeling processes such as creative thinking, problem solving, and critical thinking skills. Type II activities require students to use advanced-level research skills and provide some sort of product (i.e. written, oral, and visual communication) or demonstration of the learning that took place.
Type III Enrichment Activities involve pursuing “self-selected” areas for advanced content acquisition. The learner assumes the role of first-hand inquirer and is able to apply interests, knowledge, creative ideas, and task commitment to a selective problem. An authentic product is the result of Type III enrichment activities.
Information taken from http://www.aps.edu/aps/gifted/renzulli.html