What is difference between pub and bar?

Hello there amit8sinha, there is no difference in the meaning of the two words really. You know a 'bar' is where you can go and obtain alcoholic drinks and have a chat with some friends, a 'pub' is just an abreviation of the term 'public bar'.
The term 'pub' is used very much in Australia, few here use the term 'bar', unless they are going to a nightclub in the city. Mostly working men are to be found in the main bar room in the 'pub'. In the old days, ladies were not permitted in the mens bar, because of the things men do, like use colourful languge. Ladies would go to the 'ladies room' and families would also go to the ladies room if they were having a meal there. Today things are not so strict and the ban on women in the main bar is lifted many many years ago, but I still remember it.

I think a bar is more flashy and has more dance music. I think a pub is more earthy and cozy. I don't know if I'm right but that is what I think.

I do not visit either of them often. I only go to either of them when somebody forces me and that is basically to give company.