Why Na/C2H5OH not preferred in the reduction of carboxylic acid, despite being used for the reduction of esters
As the comments point out: the sodium in ethanol generates sodium ethoxide, just as sodium in water generates the hydroxide.  The ethoxide ion, acting as a strong base, deprotonates the acid to a salt and thwarts the reduction.  Get rid of the easily removed proton by using an ester and you unleash the reduction reaction you want.