Minimal support means minimum 2 points are enough to get Regular Spline. Minimum 3 points are enough to get a Style Spline. Therefore B-Spline can be a Regular Spline or Style Spline.
The top one is a normal Bezier and bottom is a Degree 3, so it bends the line towards the dot that you drew. You can find more explanation at Solidworks Help.
Degree 3: X^3
Degree 5: X^5
Degree 7: X^7
B-spline - Wikipedia