Mantles and mantelets are usually lumped under one term - mantle - these days, but those capes with the long trailers in front were originally called mantelets, I believe. Both have very early origins and have changed greatly over the centuries, so even though the terms are the same, they have been used to describe quite different things, very much like pannier, polonaise, crinoline and even bustle. The Victorians, for example, called the steel and cloth-tape hoop cages crinolines, a very different foundation than the frothy tulle 1950's versions, but both are correct uses of the word.