Self-Aligning Ball Bearings include a double row of balls guided by a cage and double row inner ring raceway but have the special feature of a continuous spherical outer ring raceway allowing the inner ring / ball complement to swivel within the outer ring. This is what enables a degree of self-alignment in the application.
This type of bearing is recommended when alignment of the shaft and the housing (misalignment) are a problem and the shaft could deflect. Self-aligning ball bearings are most suitable for absorbing radial forces.