Before revision: A private citizen is someone who does not have an official or professional role in a given situation.Oxford English Dictionary, 3rd edition, 2014, s.v., definition 5 The same person may be a private citizen in one role, and an official in another.
After revision: Kid friendly definitionA private citizen is the same thing as a citizen, but they have a higher role/job.Oxford English Dictionary, 3rd edition, 2014, s.v., definition 5A private citizen is someone who does not have an official or professional role in a given situation.Oxford English Dictionary, 3rd edition, 2014, s.v., definition 5 The same person may be a private citizen in one role, and an official in another.