You can already create Bézier curves:
- add a spline consisting of 3 points (start, end, and a control point). The result is a quadratic Bézier curve.
- add a spline consisting of 4 points. The result is a cubic Bézier curve.
- for higher curve degrees, create a cubic Bézier and increase the degree.
B-splines are mathematically created using another base for some reasons, see
https://wiki.freecadweb.org/B-Splines#Basis
for more details, but the result is nevertheless a Bézier. You can check this out using a math program. Create a quadratic B-Spline and Bézier using the same point coordinates and the curve follows the same path.