Because of its orientation, opposite to the working orientation of DNA polymerase III which is in a 5'to 3' manner, replication of the lagging strand is more complicated than of the leading strand.
Because of its orientation, the newly made strand is extending opposite to the working orientation of DNA polymerase III which is in a 5'to 3' manner. As a result, replication of the lagging strand is more complicated than of the leading strand.