Is it easy to apply leave for say... inspector / ASP1 ?
It does not mean that you are INSP or ASP and you can apply leave easier. Actually INSP and ASP does the same jobscope no difference. And also doesn't mean CPL and SGT is harder to go on leave.
Whether it is easier will depend on the nature of your job, where u posted to, your appointment, the work you have on hand, and so on.
I will say that if you have reasons to go on leave (say holiday) , most of the time is approved.