how much rank difference is in first counseling and second counseling?

Hey you didn't mentioned which exam you are talking about.

From general perspective the fluctuation of rank in different counselling sections , the rank depends on different perspective like Seats Vacant , average applying rank , course demanded more by students etc which cause inflation or depletion in the counselling ranks. so in general perspective no comments can be given.

For more detailed answer , I would request you to get back to career360.com (//career360.com) with some specifics of exams , the course you want to opt for etc.

I hope my answer helps you. All the very best for your future endeavors!