What is the Difference Between Similar But Different Things, Terms, and Objects

What is the Difference between Table of Contents, Index, Appendix and Annex

In this age of information and discoveries where scientists are busy in discovering new things and almost 120 pages of new information is being written on new discoveries and latest information by the scientists it has become quite difficult to pile up this mountain of information without any proper process and planning. To find the required information out of this sea of information is like finding a needle in a dark pitch night.