The difference between "shag" and "layered"

Kathryn Morris with her hair cut in a shag
 
Q: What is the difference between a 'shag' hairstyle and a 'layered' hairstyle? Why do they have different names?
 
A: The term "shag" as it concerns hairstyles refers to a short-to-mid-length layered haircut.
 
A "shag" is generally somewhere between chin and shoulder length and is cut using a stationary guide by combing the hair upward to align the hair with that found at the top of the head. The term "shag" comes from the word "shaggy" and refers to the look that was often achieved with this cut.
 
Like many names for hairstyles, "shag" was coined to appeal to a newer generation, simple marketing. In the 60s and 70s, stars like Rod Stewart, David Bowie, Leif Garrett, and Andy Gibb sported shag hairstyles. In the 80s, many of the 'big hair' heavy metal rock bands revived shag haircuts in one variation or another.
 
©Hairfinder.com
Photos by PR Photos
 
See also:
 
How to cut a shag
 
What is the definition of a shag haircut?
 
What products and items should I use to style a shag haircut?
 
Is it possible to put your hair in a ponytail when you have a long shag hairstyle?