Hii Induja,

Hope you are doing fine.

Overall rank means the rank you secured amongst all the candidates in exams inculding the unreserved category or reserved category aspirants. Category rank means the rank you got is of amongst the aspirant of that specific category appeared in the exam.l to which you belong.

All India rank (AIR) is the rank what is said the general merit rank. Whereas Category rank is what you scored in a particular category you belong such as OBC, SC/ST, -ph , EWS.

both are different, infact category rank and cut off is lower than that of the general/all india rank.

I hope I'm clear to you.

BEST wishes ahead.