As you want to get the details of difference between Union Public Service Commission and Public Service Commission so here is the information of the same for you:

UPSC conducted the exams for the exams on the whole country basis

PSU are present in every state and it conducts exams on the state basis not on whole country basis

UPSC is an examination conducted at the national level. PSC on the other hand is state level exam.

Any candidate who is an Indian can appear for the UPSC exam.

Only candidates who are residents of the state where the PSC test is conducted are allowed to apply for the same.

If the candidate clears the UPSC exam they can expect the posting to be in any part of the country