Bezier splines: Bezier splines are good for drawing shapes for illustration. The controls used to manipulate Bezier splines are similar to those found in many other drawing and compositing applications, so they may be familiar to you. Bezier controls lend themselves to the creation of precise, detailed shapes. Tangent handles adjust the curvature of the shape on either side of the control point, and this defines the surface of the shape.
B-Splines: You can also use B-Splines to draw complex shapes. But unlike Bezier splines, B-Splines are manipulated using only points—there are no tangent handles. Furthermore, the points themselves do not lie on the surface of the shape. Instead, each B-Spline control point is offset from the shape’s surface, “magnetically” pulling that section of the shape toward itself to create a curve. By combining the influence of multiple B-Spline points, you can create different curves. B-Splines are extremely smooth—by default, there are no sharp angles in B-Spline shapes, although you can create sharper curves, if necessary.
Because B-Spline controls are so simple, they’re easy to animate and manipulate. The tools you use for a specific task are largely a matter of personal preference.