Thesaurus- a thesaurus or dictionary of words with the same or nearly the same meanings, or synonyms, and their opposites, or antonyms, such as Thesaurus.com, available on the Internet or the World Wide Web, accessed through a web browser, and used by entering a query term into a search box on the site.
Dictionary- it is important to consider several advantages in the use of dictionaries. In the very early stages of learning, even an inadequate bilingual dictionary can provide an important support and be a quick reference book. In language learning/teaching process the importance of using dictionaries cannot be denied.
Glossary-A glossary is a list of terms: words, abbreviations, acronyms,etc., used frequently in a written work, giving the term and its full name, or its contextual meaning. The writer uses it to avoid the necessity of writing the full name or explaining the meaning every time it's used. The reader uses to find the meaning of unfamiliar terms or usages.
Here is why we use them