Question

how and why south Indians girls are different from north Indian girls ?
guys its my confusion

Answer 1

Who told you that they are different ... Yeah you can say that they follow and maintain their culture very well .... They are beautiful too....

Answer 2

All girls are different. There isn't any difference between girls particularly between these 2 regions. It just depends on the upbringing of an individual. 
The region they reside in doesn't matter. 
Its like keeping company. Our parents advice us to keep good company. And there's always this one friend our parents love and this one friend our parents are a little doubtful about. 
Speaking of culture and language. (language could be a barrier at times) 
We are all in the end Indians and a lot of our habits are quite similar from whatever region we come. 
So a girl from north and a girl from south can get together for their love for shopping, or the love for idli (for that matter) or the love for roti only! 
Girls are just completely different everywhere. 
The only difference is education choices, careers, jobs et cetera. 
You can't specifically say that girls from north and south are different because it completely depends on how you've been brought up, what kind of education you have been given, what kind of company you keep. 
It depends on how adjusting and flexible you are to change. 
So there is no difference between girls from these 2 regions particularly. 
GIRLS ARE DIFFERENT IN GENERAL!

1) North girls are afraid of their family, but are free-willed in their actions. South Indian girls are the opposite - they are more likely to do exactly what elders in the family say.

2) North Indian girls will often show initiative for a cause that seems attractive to them - this is not often true for south Indian girls.

3) For relationships - MONEY and JOB seems far more significant for a south Indian girl compared to their North Indian counterparts. I know I am generalizing but most of my southern acquaintances don't even take men seriously unless they are qualified to a certain extent. This is important for northern Indians too but not to the extent I have seen in south Indians that it is a pre-requisite to start dating/have a meaningful relationship. Anyone is free to correct me if its wrong.

South girls don't adjust as well as north girls - given a choice between something close to their culture, and something that isn't - they will nearly always take the option that lets them do it the way their family taught them. Be it food, or festival celebrations. In this sense north girls are more willing to at least try something new.

In South India, girls have the freedom to study further and work harder, but once they get and use that opportunity, they suddenly decide it's time to settle down and get married.