there are modern days scarves/shawls that are knit (or fashioned) in long(18 to 24 inches/a half meter or so) wide tubes, the scarf can be pulled down onto the shoulders and worn as a shawl(caplet) almost, or pulled up over the head, so the opening of the tube frames the face.(and the rest of the tube rest on the top of the shoulders)
these are still called wimples. (you can google wimple and find several patterns for knitting one)
i would define a wimples as a chin straps that extend up to the top of the head and become part of a head dress/hat/veil. they have extra fabric that drapes over the neck as well as the chin, almost like a bib.
in chaucer time, a common head dress was shaped like a crescent moon, (which sat on top of the head) and it included a wimple..
most nuns today still wear veils, very few still wear wimples.
a snood is something like a shower cap in shape, (a large circle gathered at the edges. it was used to cover/gather up the hair) snoods are often netted, or made of a fairly open/lacy like material, and worn at the back of the head, holding long hair in an ornamental net. (you might not see a snood if you only saw someone from the front.)
in NY, orthodox jewish women sometimes use closely knit or crocheted snoods to cover their hair in public (combined with a hat to cover the top of their head)
