What is the difference between an index and a glossery?

Answer 1

an index shows where a certain word or phrase is in a book, the glossary tells the definition of words in a book.

Answer 2

An index lists keywords or topics found within a document or book, along with corresponding page numbers for easy reference. A glossary is a list of terms and their definitions that are specific to the subject matter of the document. In short, an index helps with locating information quickly, while a glossary explains the meaning of specialized terms.