He is famous as a film producer.
The developer of this app is still a student.
制作者 stresses the production side of a project (e.g. film or TV) and sounds more formal, whereas クリエイター emphasizes individual creativity and sounds more casual.
制作者 is a broader term for the creator of any work (film, art, product), whereas 開発者 is used specifically for developing systems, software, or land.
Compound of 制作 (seisaku, 'production, creation') and 者 (sha, 'person'). The word follows a common pattern for agent nouns.