Reasoning for redox reactions to be classified as such
$\ce{Zn + 2AgCN -&gt; 2Ag + Zn(CN)2}$
Zinc changes its oxidation state from $0$ to $+2$, and silver changes its oxidation state from $+1$ to $0$. So, zinc is reducing agent and silver is oxidising agent.
$\ce{Zn^0 -&gt;[-2e^-] Zn^{+2}}$ (oxidation);
$\ce{2Ag^{+1} -&gt;[+2e^-] 2Ag^0}$ (reduction).
Other reactions are just equations of ion exchange without changing the oxidation states of chemical elements.