Is it table of contents or contents?

It's actually the same thing.

A table of contents is a page or pages that include information on each subject in that paticular book..

the index is found at the back part of the book while the table of the contents is found at the front part of the book

They have used printing letters and numbers. For the table of contents. They tell you how many chapters and what page is on that chapter. It only might appear at chapter books.

To show where something is in a book.