Explin the difference between a legislative referendum and a popular referendum

Legislative referendum: the governing body alludes a bit of enactment to the general population to either endorse or dismiss it by vote. Mandatory submission – Typically new constitutions must be submitted to the general population for endorsement before they are viewed as sanctioned.   
Popular Referendum : The general population may challenge a law as of late go by the lawmaking body. In the event that enough marks are assembled, the law will be put to a vote by the general population who may vote to invalidate the law