Can you explain what led to the forming of four sects in sunnis following the four Imams and how do these differ among each other.
In the beginning we see that some of the Companions of the Prophet (sws) were more learned and had more insight into the religious texts than others. They distinguished themselves in the art of understanding and interpreting the sources texts. These people settled in different parts of the empire during the time of the period of the rightly guided Caliphs. People were attracted to them and asked them questions regarding their understanding of the religious sources. They naturally attracted a very large number of students. Almost all the major centers of the empire had such great scholars from among the Companions and the successors. We know that not everyone can learn the whole texts and the details of the legal matters in there sacred texts. This happened with those who living in early Islam too. The commoners would come to these scholars and ask their views on the issues facing them. These scholars would respond to them according to their understanding of the sources. They however, never held it compulsory for anyone to follow only whet they said. The four Imams too were scholars of this stature who systematically studied the sources and gave their opinions on the issues. There followers later on developed a feeling of strong association with their teachers. The scholars of the town were preferred over the foreigners. With the passage of time this strict association became customary and the spirit of original research and objectivity vanished to be replaced by a kind of bias which led the people to follow what their own scholars would hold. It was only the semi-scholars who were not firmly grounded in knowledge who helped in spreading this blind attachment and following. There were many other great scholars like the four imams. Their names did not survive for they did not have brilliant students who could work further and develop their approach. Gradually their thought and views became extinct. Thus the entire sunni Muslim community followed these four school of thought.
As for the nature of difference in their approach, it is the difference of principles of interpreting the texts and determining the status of the knowledge ascribed to the Prophet (sws) and its relationship with the word of God where these people differ.