These tools in the Create Curves toolbox are used to place the following special types of 2D B-spline curves.

The Conic Curve tool is used to place a conic section — a hyperbola, parabola, or partial ellipse.

The Spiral Curve tool is used to place a transitional spiral — this is most commonly used for highway design.

The Interpolation by Arcs tool is used to place a complex chain of arcs that passes through a given set of points.