There is no comparison between the two situations … India and Pakistan wanted independence from Brirtish Raj because they were occupied lands.
The major difference being … Indians were not part of the British democracy … they could not elect the people who sat in the parliament in UK. They were given a token government which was answerable to the British crown not the other way round.
I have said it before also … if Nehru or Jinnah could have become PM of Great Britian … frankly they would have no objection to being part of the british empire. Infact Gandhi was working for the British in South Africa and only when he was treated as a second class citizen did he he join the independence struggle.
Now coming to Kashmir … it is very much a part of India in all sense… Kashmiri leaders have been elected to the parliament and have been senior ministers in the Union Cabinet. They are part of the democratic fibre of India.
The present situation has various factors … internal and external dimension …