Hello.

Common merit rank is more important, as you are called for counselling on its basis. Category Merit Rank is for reserved quota seats. So if you’re a general, your category merit rank doesn't hold much importance.

Each centre allots 30 seats for every course out of which 7-8 seats r for obc's,15 for generals and 5 and 4 for SC n ST respectively.CMR shows your overall rank in the entrance whereas category rank shows where do you stand among your category people.

You are called in the counselling according to your Common Merit Rank(CMR). Now, if you belong from General category, Category Rank is of no use to you. But if you are eligible for reservation in any category, Category Rank is of utmost importance to you. Because then, you will get preference according to the numbers of vacant seats in your category. Category Rank is vital only for reserved candidates. 

Hope this is helpful.

Good luck.