That's a good question. I don't think there's very much of a difference between those concepts. In fact I think much of the jurisprudence that deals with citizen's arrest when it comes to the core issues of “finds committing” and the nature of the offences and so on...the jurisprudence that deals with arrest by peace officers is looked to when a court is dealing with an arrest by a citizen. In other words, when we are talking about arrest without a warrant, which the police also have the power to do in certain circumstances, the elements would be interpreted in much the same way. So there would be consistency there.
On March 6th, 2012. See this statement in context.