Hello, 

It is not the same. The application number is the number of CLAT 2018, generated after the candidate will be applying for the common law admission test and the registration number and password refers to the Information the candidate has to provide to download the hall ticket. 

Please visist https://law.careers360.com/articles/clat-admit-card-important-details to see an image of the admit card, it will help you understand better. 

Hope this helps you and good luck!