Difference between Mongolian coats "terleg" and "deel"
The terleg is a garment designed to be as simple and plain as possible. As it is often used as an undercoat, its main purposes are to fit to the body, to warm up the owner, and to be obscure. Opposed to it, the deel is an outer garment. It is designed to look ornate and festive. Also, winter deels are supposed to protect the owner from harsh weather conditions.
To learn more about these two garments, read the article here: http://nationalclothing.org/asia/57-mongolia/177-difference-between-mongolian-coats-terleg-and-deel.html