How is south Asia diffrent from east Asia?

Because it is in the part of Asia in the most South East Part

A line

less densely populated

This really depends on the context of how you are using it. All such labeling is purely arbitrary. If you are talking about the large scale mass as a continent than it is simply Asia. However, any...

Southeast Asia has a mix of religions ranging from Buddhism (which is very strong in Burma and Thailand) to Islam (which is very strong in Malaysia and Indonesia) to Christianity and Chinese Faiths...