united states - What exactly is "campus security"?

I read this question where a teaching assistant asks how to deal with an aggressive student.

In her answer, the user Nicole Hamilton gives advice to call campus security. Now, in my naive foreign thinking, whenever the word "campus security" came up, I imagined this to be similar to a discotheque's security people: a single strong person (or a team) who would be in the university building during its opening hours, helping de-escalate conflicts and throwing out aggressive people.

However, the user "apparente001" advises the OP to "do not hesitate to call campus security for an escort while leaving your building at night" (in a comment). This suggests that campus security is more: A university employee apparently may call these security people at any time to any (reasonable?) place to escort them (I assume, provided that some incident happened like the one described by OP). From the Wikipedia article, I understand campus police (is this the same as campus security?) to be police officers who only serve in university.

However (at least in my country), I could not simply call the police to escort me at night when something "vague" like the incident described in the question happened. (I do not want to say the the incident is not serious - however, I doubt a police officer would escort me at night if I told them that very incident).

So I take it that campus security/campus police must be something different: an organisation any university employee can call at any time. Can you tell me more about this concept?

In particular, the question which interest me are:

1. 
   

   Is campus police/campus security the same concept?

   
   


2. 
   

   What exactly does campus police/campus security for university employees? When can they be called and for what purpose?

   
   


3. 
   

   Can university students (if they are not at the university building) also call them? If yes, to what extend do they help them?

   
   
   

While the original question specifies no country, I have the feeling that the OP and the user "apparente001" are talking about US or Canada. (I may be wrong, through.) Therefore, I also would be (mainly) interested in information about these countries.