NaHSO4 = Na+ + HSO4- Are the results in the first solution. The Na+ ion comes from a strong base NaOH and would rather stay in the solution state then couple with the OH- from the water. The HSO4- is from the strong acid H2SO4 and does not attract the H+ from the water. So the solution is neutral or pH = 7
In the second case the Na+ as before comes from a strong base and doesn’t attract the OH- from the water to free the H+ remaining of the water molecule. However, the HCO3- is the ion from a weak acid and attracts the H+ of the water molecule leaving the OH- ion free to affect the pH of the water making it basic or above 7.
In both cases above the OH- and the H+ come from the dissolution of the H2O molecule by the equilibrium H2O = H+ + OH- . in the second case as the H+ attached to the HCO3- the equilibrium is shifted to the right producing more OH- giving the solution its basic characteristics.
Both word mean the same thing. Ions are formed and a solution is created.
Hope this helped.
