How is 'cast iron' different from 'pig iron'?

(N/A) The iron obtained from blast furnaces is known as pig iron. It contains around $4 \%$ carbon and many impurities such as $S$,$P$,$Si$,and $Mn$ in smaller amounts.
Cast iron is obtained by melting pig iron with scrap iron and coke using a hot air blast. It contains a lower amount of carbon (about $3 \%$) than pig iron. Unlike pig iron,cast iron is extremely hard and brittle.