Originally Posted by rickair7777

You would expect them to be similar.

Va is the max speed where full and abrupt control movements will not destroy the airplanes structure. Either the wing will stall first, or the airflow over the control surfaces is insufficient to generate damaging force. DANGER: Va may not, and probably does not, apply to the rudder on transport category aircraft (not sure about non-transport)...see AA 587 for more details.

Vb basically protects the wing from gust loads by ensuring the wing will stall before gust loads generate damaging forces.