Pig iron is generally an intermediate product of the wrought iron and steel making process. Pig iron is virtually useless due to the very high impurity content. "Pure" is a strange quantification of the comparison between pig iron and wrought iron. Pig iron is pure pig iron and wrought iron is pure wrought iron if there is a "standard" for the respective materials. I'm guessing that the answer you want is that wrought iron is "more pure."

iron core , coke and limestone are needed to make pig iron

Pig iron is crude iron as first obtained from a smelting furnace, in the form of oblong blocks.

The main impurities in pig are carbon (C) and Silicon (Si)

iron core , coke and limestone are needed to make pig iron