Salt dissolves faster in water than it does in baking soda. Salt and water have a similar polarity to water, which generally increases dissolution speed.
Salt and baking soda are both ionic compounds, but there is an increased number of ionic bonds in baking soda than in table salt. Ionic compounds take longer to break down in water because their bonds are much stronger. Less sodium bicarbonate dissolves in the same temperature water as sodium chloride. In ice water, only 6.9 grams of sodium bicarbonate dissolves, but 35.7 grams of sodium chloride would dissolve. Temperature and water volume would alter dissolution rates.