How is the variability in oxidation states of transition metals different from that of the non-transition metals? Illustrate with examples.

(N/A) In transition elements,the oxidation states differ by $1$ unit (e.g.,$Fe^{2+}$ and $Fe^{3+}$,$Cu^{+}$ and $Cu^{2+}$) because the energy difference between $(n-1)d$ and $ns$ orbitals is small.
In non-transition elements,the oxidation states typically differ by $2$ units (e.g.,$Sn^{2+}$ and $Sn^{4+}$,$Pb^{2+}$ and $Pb^{4+}$) due to the inert pair effect.