Diploma

If you are doing Diploma in mechanical engineering after class 12th, then you can apply for JEE Mains. Else, you will be eligible to appear for JEE Mains in final year of Diploma in engineering.

You can take admission in B.Tech 2nd year through lateral entry.

The eligibility depends on the type of course that you wish to pursue.
The details of some courses is stated below:
1. Diploma: Class 10th pass from a recognized board with minimum 40% marks.
2. Bachelor's degree: Class 12th examination with at least 50% marks.
3. Post-graduation degree: Bachelor's degree from a recognized university with at least 45% marks.
You can visit the below mentioned link for some top ranking institutes:
https://hospitality.shiksha.com/travel-and-tourism-courses-in-india-categorypage-6-86-1-0-0-1-1-2-0-none-1-0

Hi,
Here is the detail:
Post Diploma in Information Technologies:
First Semester:
Tuition (4 courses x $1,195 per course): $4,780
Lab fees (4 labs x $160 per lab): $640
Material fees: $600
Registration fees: $350
Medical insurance: $300
CNC extended medical (payable yearly): $260
Books: $500
Total for one semester: $7,430
Total for program (two years): $30,915

Diploma is what you pursue after your high school (12th grade) and post graduate diploma is what you pursue after graduating.

You are eligible for lateral entry admission in B.Tech aeronautical engineering after completing Diploma in mechanical engineering. You can evaluate Manipal Institute of Technology for B.Tech in aeronautical engineering.

To get admission in NIT, a candidate must appear for JEE Mains. Unless, you appear for the entrance exam you won't get admission in National Institute of Technology. The eligibility criteria for entrance exam is class 12th with PCM as the subjects.
Apart from IIT and NIT, most colleges in India offer lateral entry for Diploma students. These colleges do reserve some seats for lateral entry students.
All the best.

Dear Ramees Jouhar,
Yes, you can opt for SAP material management course, which is related to you.
All the best.