Position in Vector (C#)

Hey,

I am trying to store a position in a vector3. I was able to do it in JS:

 var movementThisStep : Vector3 = myRigidbody.position - previousPosition; 

But when I try to do it in C#, I get an error message. I have tried to do it this way:

 Vector3 movementThisStep = new Vector3 (myRigidbody.position - previousPosition);

And got this error message: The type `UnityEngine.Vector3' does not contain a constructor that takes `1' arguments