Vector2 and Vector3 Dilemma and objects

I am having many problems with these different scenerarios:

Vector3 pos = New Vector3(0,0,1);
Why do we use the keyword New, many people say that to create a vector3 Object, but I don’t understand what exactly an object is and why we need to create this.

Vector3 pos = Vector3.up
What is the difference between this and the first scenario and is Vector3 in Vector3.up an object.

  1. And when do we need to use only one
    Vector3(), Without the Keyword New

I would recommend your to read something about OOP, it can clear many things.
By “new” you make an instance of class - types(but not only, look there) are simply objects - string, int, float… and Unity’s Objects vector, gameobject etc. So if you want to use object, you need create it first.

Vector3.up is Shorthand for writing new Vector3(0, 1, 0).