What is the difference between an act, rule, bill, ordinance

An act is one which was conceived as a bill, grown up as an ordinance and matured as an act. Means a bill is an idea which after getting passed by both the houses of parliament becomes an ordinance and then after the assent of the president becomes a statute.circulars are informations while notifications require to be adhered

Agree With Doveson 

1. When both houses of Parliament are not in session and there is need for urgent legislation, an Ordinance is issued which has the same effect as an Act. It  requires to be approved by Parliament otherwise it lapses.

2. If Government wants the provisions of the ordinance to continue, it introduces it in the form of a Bill which must be passed by both Houses of Parliament. After receiving the Assent of the President, it becomes law but notification must be issued to bring it into effect from a specified date.

3. Notifications and circulars are issued by government under various Acts to clarify the provisions of law. There are provisions in the Act which specify that a particular Section shall come into force when notification is issued.