There are several buffers in natural seawater that make up Alkalinity. BiCarbonate and Carbonate are the major components of alkalinity by far followed distantly by Borate. Carbonate is the molecule corals, clams, snails, etc, use to built their Calcium carbonate skeleton. The ratio of Carbonate to Bicarbonate in saltwater is determined mostly by PH so as Carbonate is used up by animals Bicarbonate is converted to Carbonate to maintain the ratio.
"Baked" baking soda is nearly pure Carbonate, often called washing soda. Baking Soda is nearly pure Bicarbonate. As I stated before, the ratio of these two molecules is determined by PH so in the long term it does not matter which you add to your tank. Carbonate will tend to raise PH when added because it will raise PH as it converts to Bicarbonate. The effect is only temporary though.
Mrs. Wages is Lime - Calcium hydroxide - no relation to baking soda.