Are you talking location or size, or both?
Circular interpolating can introduce error by deflection and the accuracy of the CNC machine. When you say plunging, are you talking about creating a hole the size of the endmill?
If the CNC machine was tight with no backlash then the results should be the same. I believe it could vary from machine to machine what to best method would be. I've seen machines with backlash where they had to always travel the same direction when approaching a hole location and then plunge to get the most accurate result. If they had to move to a hole in the other direction they would travel past the hole and come back. It sometimes is a matter of trial and error to see what method is best in each case.
If the CNC machine was tight with no backlash then the results should be the same. I believe it could vary from machine to machine what to best method would be. I've seen machines with backlash where they had to always travel the same direction when approaching a hole location and then plunge to get the most accurate result. If they had to move to a hole in the other direction they would travel past the hole and come back. It sometimes is a matter of trial and error to see what method is best in each case.
