The UPSC preliminary exam differs from the mains in structure and purpose. The preliminary exam is an objective-type test, designed to screen candidates for the further stages of the selection process. It evaluates general studies, aptitude, and current affairs knowledge, serving as a qualifying round with no marks carried forward. In contrast, the mains exam comprises descriptive-type questions, focused on in-depth analysis and understanding of various subjects relevant to public administration. The mains include diverse papers such as essay writing, which allows candidates to demonstrate critical thinking and analytical abilities. Together, both exams ensure a comprehensive assessment of candidates' readiness for civil service roles.