Bangladesh and India are known to be two different countries. Their time difference is only 30 minutes, which is probably why some people may get confused that they are actually different from each other. It should be remembered that in India, the people there are multilingual. There are different languages that are still being spoken by people there.
In Bangladesh, they are monolingual. No matter what part of the country they would visit, they can already expect that the language is going to be the same. 98% of the population will speak that language, although there are also some of them who are beginning to speak English.