Must to draw cubic curve and modify as B-spline?

In AutoCAD R14, when I move the mouse over the spline button, on the bottom state bar, the tip says "Creates a quadratic or cubic spline
[NURBS] curve spline: spline". Then, I press mouse left button the draw a curve shape like 'M'. I wanna know , the curve I draw is a "quadratic" or "cubic" spline curve, or B-spline curve? And then, I select "Modify" -- "Object" -- "Spline", and the curve I draw just now, I find the control point is changed, the behavior is some like B-spline. My second question is : Must it be change to B-spline when we want to modify the curve we draw using cubic spline way?
Thanks.
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