Madheshi vs. Madhise/Madhishe/Madhesi/Madesi:
Madheshi are the residents of Madhesh. Madhesh is formed from ‘madhya’ (mid) + ‘desh’ (country), but the origin is sometimes also attributed to ‘matsyadesh’ (the country of fish).
On the other hand, Madhise/Madhishe is a slang, “nepalicized” version of Madheshi, used often as derogatory term to refer Madheshi by hill people. Madhesi/Madesi, with ‘s’ instead of ‘sh’ or ‘d’ instead of ‘dh’ are also nepalicized version. Madheshi, with ‘dh’ and ‘sh’ should be preferably used, in the original forms, rather than using Madhesi, Madesi, Madhishe or Madhise.
Terai/Tarai vs. Madhesh:
Terai or Tarai (presumed to be derived from Persian language to mean ‘damp’ or ‘moist land’) is used to refer to all the region of northern India and southern Nepal running parallel to the lower Himalayan ranges, from the Yamuna River (west) to the Brahmaputra River (east).
In present day, Madhesh refers to a 26 to 32 km wide broad belt of alluvial and fertile land stretching from Mahakali river (west) to Mechi river (east) between Indian border (south) and Sivalik/Chure Range in North.
Madheshi vs. Tarain/Terain/Tarayan:
Madheshi refers to native inhabitants and aborigines of Madhesh, whereas Tarain/Terain/Tarayan can refer to anyone living in Terai region of Nepal, including hill-migrants.
Madheshi vs. Nepali Identity:
From historical point of view, the identity “Madheshi” connects people living in Madhesh with their thousands years of history of living in Madhesh, whereas identity “Nepali” refers to their 200 years of history since the conquest of the region by Shah rulers. So people living in Madhesh are Madheshi first (thousands years of history), and then Nepali (mere 200 years). From the cultural perspective, the word “Nepali” has been used in such a stereotypic way that none of the characteristics of Madheshi people and culture, whether it’s language, dress, foods, rituals or festivals fit into their prototype of Nepali (but surprisingly someone living in Darjeeling or Burma qualifies for being Nepali ). So from cultural perspective, the word “Nepali” doesn’t include anything of Madheshi and is inappropriate for Madheshi.
Nation vs. Country:
People often talk about Nepalese “nationality” or Nepal as a “nation”, both of which are inappropriate. Nepal is a country, with large number of different nations, not a single nation. The word “nation” comes from Latin word ‘natio’. In the words of Wikipedia:
“A nation is a group of humans who are assumed to share a common identity, and to share a common language, religion, ideology, culture, and/or history. They are usually assumed to have a common origin, in the sense of ancestry, parentage or descent.”
In Nepal, people came from different origins, have different languages, religion, culture and history; and thus Nepal cannot be called a nation, and there is no such thing as Nepalese “nationality” or “nationalism”. It was King Mahendra who tried to manufacture it out of nothing, forcing “Autai Bhasha, Autai Bhesh” [One Language One Dress] (in the country where more than 60 languages are spoken!).
Nepali vs. Khas Language:
Thesedays Nepali is often used to describe ‘Khas’ language. However Nepali should originally refer to language of Nepal (then Kathmandu valley), which is Newari. After the invasion of Kathmandu valley by Shah rulers from Gorkha, they didn’t only borrow(?) the name Nepal for theconquered territory, but also the name ‘Nepali’ to describe their own lanuage, Khas. The consequence is: thesedays Newari language has to be, unusally, called ‘Nepal’ language (possibly even violating normal grammatical rule).
(Source: madhesh.bravehost.com)