arrhenius concept-

acid are substances which give H+ in aqueous solns

bases are substances which give OH- in aqueous solns

Ionic product of water is the equilibrium constant for a reaction in which water acts both as an acid  and base

solubilty product-

it is the product of the concentrations of the ions, with each concentration raised to a power equal to the coefficient of that ion in the balanced equation for the solubility equilibrium.