CAT

Some basic pointers:
SNAP stands for Symbiosis National Aptitude Test. It provides admission to the 15 Symbiosis Institutes. Some of the premier colleges which one can apply for through SNAP include SCMHRD and SIBM. So how does SNAP fare in comparison to CAT. To start with, SNAP is considered to be relatively easier than CAT. The type of questions asked is also not wildly different preparation for CAT. Creates 80% of the groundwork needed for SNAP while CAT has MCQs and subjective questions, SNAP only has MCQs. So if the worst comes to worse, you still have a 1/4 chance to get marks in SNAP versus the subjective questions in CAT. This matters, since one question could be the difference between you and your dream college.
To conclude, SNAP and CAT are gateways to top colleges in the country while CAT fives entry into 150+ institutes, SNAP is for the 15 Symbiosis colleges in India which provide with an MBA degree. You need to research to figure which course suits you best. Some courses, such as the MBA in infrastructure management or business analytics are niche courses which have a lot of scope but are not talked about that much. Always apply for all the exams, you never know what might work for you. From an exam point of view, in case you are a candidate who feels that cutoffs will be a constraint in your admissions process and are able to manage time well, SNAP is your type of exam.