Geographically speaking, there are two main areas of dispute between India and China.
The first is in the area of the Indian province of Jammu and Kashmir. There is an area there called Aksai Chin that is claimed by both China and India. India feels it is part of Jammu and Kashmir while China feels that it is part of Xinjiang province. This area is at extremely high elevation and has essentially no tangible value. It is a desert.
The second area is to the southeast of Aksai Chin. This areas borders Tibet,Bhutan, and Burma. This is an area that the Chinese call South Tibet and the Indians call Arunachal Pradesh. Disputes here center around Chinese claims to what is their "traditional" territory and Indian claims based on boundaries laid out in a haphazard way by the British when they controlled India. Here, too, the disputed areas are mainly at high elevations in the Himalayas.