UPSC conducts the Civil Services Exam for all-India services like IAS, IPS and IFS, with postings anywhere in the country.
State PCS exams recruit for the state civil services — SDM, DSP, ETO and similar posts within one state.
Both have prelims, mains and interview, but the syllabus, state-specific papers and language requirements differ.
PCS posts carry state-cadre authority, while UPSC services can rise to central government positions.
Choose based on where you want to serve and the exam pattern you are comfortable with.