Usually yes, however the answer is based on local or department policy so there is no universal answer.
There can be lots, a few are Patrol Officer, Security Guard, WatchMan
a sheriff, body guard, or a security officer(:
no, a peace officer in California is a person who has completed POST and is employed by a law enforcement agency, i.e. sheriff or city police. A security guards job is to observe and report, and sometimes protect.
Private Investigator, Loss Prevention Officer or Security Guard
yes
Policeman sheriff Fireman Security Guard Correction Officer
a sworn officer wears blue and can arrest criminals while a security guard wears white and can't arrest people
You have to employed by the private security company who has the security contract with the government. Most of the times some government building do not want to hire armed security people. Government buildings want armed security guards to be qualified as SPO. you will be working as an Armed Security guard but your title will be SPO (Special Police Officer).
doctor security guard bartender police officer nurse
If there isn't a valid reason for that police officer to be doing that (e.g., the post is part of an active crime scene), absolutely.
A railroad may have its own private police force that can be anything from a Security Guard to a fully trained Police Officer. A Railroad Detective is a member fully trained Police Officer that works for the railroad.
Yes they train you to be a police officer and soldier (kind of)