In English, Soutane is the same as a cassock, however originally they were two different types. The long clerical robe that priests used to wear and some still do is
now called a cassock or soutane. In other European countries, it is not called a cassock but a soutane.
Germany: Talar or Sutane
France: Soutanne
Poland: Sutanna
Italy: Talar
The point is, the cassock is really the Anglican version of the Roman Soutane. Technically, cassocks are double breasted and are Anglican, while Soutanes are single-breasted and Roman Catholic. But, I guess Soutane sounded to French, and so we started calling them cassocks. However, there is a distinction, but we interchange cassock and soutane since cassock I guess sounds more English. A soutane and simar is different also, which you guys were talking about. But, I just wanted to let people know that technically a cassock is anglican, and a soutane (which we should be calling it) is Roman Catholic. But, the term cassock is now accepted, and we all know what we’re talking about.
According to an Anglican book, this was published in the late 19th century, the bishop (author) explained that an Anglican cassock had no buttons and was double breasted, while a Roman Catholic soutane (and he said this with a little disdain in the book) has traditionally 33 buttons and is single-breasted.
Here’s a link on google books, its on page 118:
books.google.com/books?id=w1IQAAAAIAAJ&pg=PA118&dq=Anglican+cassock+double-breasted+no+buttons+soutane
I say, we start calling them Soutanes again! Cassocks are for Anglicans!