Yes Kushagra, there is another national level examination for architecture which is substitute for NATA. But the participating colleges for NATA is SPAs and for JEE MAINS paper 2 the participating colleges are NITs and IITs also the conducting body of NATA is CoA and for JEE mains paper 2 is NTA. 

WHAT IS IIT JEE? 

IIT stands for Indian Institutes of Technology, a group of autonomous prestigious engineering and technology-oriented institution of national level. And JEE stands for Joint Entrance Examination, an engineering entrance exam conducted to get admission in various Indian engineering colleges and institution. JEE conducts by the Joint seat allocation authority. There are two different types of JEE:

1. The JEE-Main 2.
2. The JEE-Advanced. 

There are total of 23 IIT, 31 NIT, 25 IIIT campuses and other Government Funded Technical Institutes (GFTIs), which take admission on the basis of JEE score. 

JEE MAINS 

Joint Entrance Examination – Main or popularly known as JEE-Mains, or can be said All India Engineering Entrance Examination (AIEEE), is an national level entrance examination to take admission to various technical undergraduate programs like B. Tech, B. Arch etc across colleges in India. The exam is conducted by the National Testing Agency. It is usually conducted twice every year.

JEE MAINS CONSISTS OF ONLY TWO PAPERS:

Paper 1 and paper 2.

Paper 1: it is for B.E./B.Tech courses
Paper 2: it is for B.Arch and B.Planning courses.

JEE MAINS PAPER 2

ELIGIBILITY CRITERIA FOR JEE MAINS PAPER 2

• There is no age limit specified by NTA to sit for JEE Mains paper 2. 
• Candidates appearing for JEE Mains Paper 2 must have Mathematics in their Class 12. Candidates must have pass their 10+2 examination with 50% marks in Physics, Chemistry, and Mathematics subject combination. 

EXAM PATTERN FOR JEE MAINS PAPER 2

JEE Mains paper 2 is divided into 3 sections. 

• Part- 1 for Mathematics will be conducted in computer based online mode. This part is common for students who are interested in both B. Arch and B. Plan. 
• Part-2 for General Aptitude will be conducted in computer based online mode. This part is also common for students who are interested in both B. Arch and B. Plan. 
• Part-3 as Drawing/Planning depending upon the candidate's choices for B.Arch/B.Plan. For B. Arch students this part will contain drawing questions and for B. Plan students this part will contain general questions from planning. This part will conduct in offline pen and paper based mode. 

DURATION OF EXAM

• This exam is for 3 hours in general. 
• 3 and half hourse will be given to the candidates with both B.Arch and B.Plan
• 4 hours will be given to candidates with disabilities and have physical limitation to write. 

TOTAL NUMBER OF QUESTIONS

• 82 for B.Arch (Mathematics 30, Aptitude 50 and Drawing 2)
• 105 for B.Planning (Mathematics 30, Aptitude 50 and Planning 25)

JEE Mains paper 2 will have negative marking. 4 marks will be awarded for every correct answer; 1 mark will be deducted for every wrong answer. 

Hope this helps!