The 4 imaams differences

This is a lenghty academic discussion and deliberation.
See Hadhrat Sheikhul Ahadith Moulana Zakariyyah Saheb's (A.R) "Al - Itidaal".

Also Shah Waliyullaah (A.R), "Hujjatullaah Baalighah". Due to the variant principles (usul) of jurisprudence, Tafseer, Ahadith, Sunnat which resulted in differences in "Usul" in Shari analogical reasons and seperate interpretations of sources of argumentation led to modification in the codification of terminologies. To understand the above enquire from reliable Ulema to explain the diversification of this specified science.