Using washing soda ($Na_2CO_3$) to clean greasy utensils is like using strong detergent, whereas taking an antacid ($NaHCO_3$) for acidity is like sipping a mild, soothing soothing mixture — you would never drink heavy-duty laundry detergent for a stomach ache!

Bicarbonate for Belly (stomach), Carbonate for Cleansing (washing soda).

Sodium carbonate in aqueous solution undergoes strong hydrolysis to form sodium hydroxide and carbonic acid, rendering the solution strongly alkaline ($pH > 7$). In contrast, sodium bicarbonate ($NaHCO_3$) is a mild alkali capable of safely neutralizing excess hydrochloric acid ($HCl$) in the stomach without causing caustic damage: $NaHCO_3 + HCl \rightarrow \text{Na Cl} + H_2O + CO_2\uparrow$.