Difference between NurbsCurce.ByPoint(Points, Degree=3) and NurbsCurce.ByPoint(Points)(Degree=3 by default)

Hi, I am confusing about NurbsCurve, what I want to do is find the edge of a floor (segment of Cuves), create structural beam with StructuralFraming.BeamByCurve() after offset part of the edge.

But first I found I could not use PolyCurve.ByJointCurves(). Then I found NurbsCurce.ByPoint(Points, Degree=3) and NurbsCurce.ByPoint(Points)(Degree=3 by default) gives me different results.

I also want to know what is the best way to create structural framing along the cuves? Create a Revit element then delete it ?

I uploaded the .dyn and Revit file . Thanks in advance for any suggestions.
Break Beam At Grid 00.dyn (7.5 KB)


Spline.rvt (1.9 MB)