You are going to get different answers from different people because there is no federal standard or definition for that term. In Illinois it is as follows:
(720 ILCS 5/2‑13) (from Ch. 38, par. 2‑13)
Sec. 2‑13. "Peace officer". "Peace officer" means any person who by virtue of his office or public employment is vested by law with a duty to maintain public order or to make arrests for offenses, whether that duty extends to all offenses or is limited to specific offenses.
State statutes also call for police officers which are appointed to enforce the state statutes. All police officers are peace officers but not all peace officers are police officers (if that makes sense?)

Thanks for the explanation. I guess it varies from state to state (or town to town). Best thing to do is call the department that is hiring a peace officer and ask. Thanks again!