Rajas of mahajanapadas :
(i) They became Raja by performing very big sacrifices where people accepted their Supremacy.
(ii) They had capital cities, which were fortified. They also had large Armies.
Rajas in Rigveda :
(i) The rulers were chosen by the Janna i.e. the people.
(ii) They did not have Capital city, palaces and Armies. Also they did not collect taxes.