I'm sorry I didn't understand your question. Were you asking about the difficulty level between the NCLEX-RN and a Master's degree in nursing? Just from my own perspective, sitting for the NCLEX-RN does not compare to the difficulty I experienced from attending graduate school. Realize that the the NCLEX-RN tests your competence as an entry-level RN. Questions are aimed at the "generalist" nurse, not a "clinical expert". On the other hand, a master's degree in nursing should be aimed at preparing nurses who are ready to practice at an advanced level. Courses are taught to build up on knowledge learned in your BSN program, hence, the course title "Advanced Pathophysiology" instead of "Pathophysiology" which you probably already had in your BSN.
The ideal way is to graduate from your BSN, gain work experience, choose a specialty of interest, and pursue a graduate degree in your specialty of interest (such as "adult health", as you mentioned). Unfortunately, some schools
in the Philippines seem to be allowing a "fast-track" approach to specialization for nurses who have no clinical experience to build up on. Given that it's so hard to find a job there as a nurse, I am inclined to say I don't blame you for wanting to keep busy by continuing your studies. Good luck in whatever you plan to do.
BTW, I got my MSN here in the US, if that makes a difference.