Hi Harshith,

For IIT there is only one exam which is JEE ADVANCED. However, before that, you have to give another exam JEE Mains and qualify it. Only then you are eligible for JEE ADVANCED. Moreover, you should also be in your top 20% students among your board. For CBSE that is around 80% and for UP board around 70%. If you fail this 20% criteria you are not eligible for admissions in IITs. 

Now for the main exam part, there are to exams:-

• JEE MAINS
• JEE ADVANCED

Syllabus for both the exams will be quite same with some minor changes however, the level of Advanced is far more than the Mains. As you are preparing for IITs here are some helpful links for you:-

https://engineering.careers360.com/articles/how-prepare-for-jee-main
https://engineering.careers360.com/articles/jee-main-preparation-tips
https://engineering.careers360.com/exams/jee-advanced
https://engineering.careers360.com/articles/jee-advanced-preparation-tips-physics-chemistry-and-mathematics

Hope this helps.

Thank You.