Aeronautical engineering is equivalent to B Tech Engineering Aeronautical Engineering is four Years Full time course .it is the course of the research, construction ,design, testing ,development, science and technology of aircraft and spacecraft.

Aerospace engineering is a research with the design, construction, and study of the science behind the forces and physical characteristics of aircraft, rockets, flying craft, and spacecraft and also covers their aerodynamic properties and behaviors, airfoil, control surfaces, lift, drag, and other properties.

Eligibility criteria for a BE / B.Tech in Aeronautical engineering is
10+2 or equivalent examination, with Physics, Chemistry and Mathematics and must have a high percentage of marks in the aggregate.
To get admission in IIT's is : 'JEE' entrance exam
For other institutions : their own separate entrance exams and other state level and national level exams.
Age should not be more than 20 Years.

You can apply in following best engineering exams :
IITJEE: Indian Institute of Technology Joint Entrance Exam
AIEEE: All India Engineering Entrance Examination
BITSAT: Birla Institute of Technology and Science Aptitude Test