They are called tangential extractors because the arrangement of the frame inside the extractor is tangent to the barrel, i.e. perpendicular to the radii of the box. As the frames are further away from the centre of rotation, they allow a stronger centrifugal force on the honeycombs and therefore a "deeper" extraction of the cells with respect to the radial ones is obtained. Especially with the viscous honeys and in large paintings such as Layens and Dadant of breeding chamber.
If you use a tangential extractor, you will have to turn the frames manually to get the honey out of both sides.