"Washing soda" = "soda crystals" = sodium carbonate = Na2CO3
"Bicarbonate of soda" = "baking soda" = sodium hydrogen carbonate = E500 = NaHCO3
"Baking powder" = bicarbonate of soda + one or more acid salts. Typical formulation : sodium bicarbonate + monocalcium phosphate + sodium aluminium sulphate.
Only the first is of any use for releasing caramelised sweet-and-sour sauce from the base of stainless-steel saucepans !
** Phil.