Hydrolysis and Hydration
Hydrolysis is reaction with water, forming usually 2 different reaction products. It can be also named decomposition by water.
Hydration is (usually) reversible chemical bonding of water. It can be also named water addition.
One action of above can preceed or follow the other. If the hydration step preceeds hydrolysis in the reaction kinetics, the distinction may look vaque from some points of view.
Ammonium acetate undergo hydrolysis.


$$
\begin{align}
\ce{CH3COONH4 &amp;-&gt; CH3COO- + NH4+} \\
\ce{CH3COO- + H3O+ &amp;&lt;=&gt; CH3COOH + H2O } \\
\ce{CH3COO- + H2O &amp;&lt;=&gt; CH3COOH + OH- } \\
\ce{NH4+ + H2O &amp;&lt;=&gt; NH3 + H3O+} \\
\ce{NH4+ + OH- &amp;&lt;=&gt; NH3 + H2O} \\
\ce{2 H2O &amp;&lt;=&gt; H3O+ + OH-}
\end{align}
$$