IIHM eCHAT

Scope for NCHMCT JEE is much better as compared to IIHM eCHAT as mentioned below. In my opinion if you have a choice between the two, you should opt to appear for the NCHMCT JEE.
International Institute of Hotel Management (IIHM) conducts an Electronic Common Hotel Admission Test (eCHAT) to offer admission to candidates in hotel management programs on offer by the institute. This entrance test is also known by the name of Combined Hospitality Aptitude Test.
IIHM entrance exam is a national level test. After clearing IIHM eCHAT candidates are further shortlisted for admissions on the basis of their performance in the group discussion and personal interview round.
or
By clearing NCHMCT JEE 2018, candidates can secure admission in 21 Central Institutes of Hotel Management, 22 State Government Institutes of Hotel Management, one Public Sector Undertaking and 14 Private Institutes of Hotel Management affiliated with NCHMCT. Apart from this, a total of 12 Food Craft Institutes, 2 SIHMs (running only Diploma level programme). All these colleges offer standardized course curriculum as prescribed by NCHMCT for the various programs that they offer.
Regards.

While preparing for IIHM e CHAT -
Students can use various reference books. (Check this link for books for preparing IIHM eCHAT exam -
https://www.shiksha.com/hospitality-travel/hotel-hospitality-management/articles/books-to-read-for-iihm-echat-2015-blogId-10109)
Join good coaching centers, there are several good centers which give coaching to the students to clear the exam.
Take as many mock tests as possible. Mock Tests are undertaken by the students to identify the weak sections. Make more effort for such topics.
Make a study plan and follow it strictly. You will definitely clear the exam.
Students should develop a realistic plan that is established according to the needs and the schedule, and supports the way he/she learns.
Students should stick to the study plan and learn at a comfortable pace.