I have friends over in Afghinstan and family who have served overseas...and my ENT doctor is Muslim...there is a lot of confusion in Western culture about the hijab and burqa...
In the Islamic culture - dress is about modesty. It also is a custom as well as social class...
The attire you are talking about - the burka or burqa - is the "Conservative" choice for some Muslim women. As her beauty should ONLY be seen by her husband. Hence the veil (hijab in Arabic).
The Hijab you see women in Western cultures is typical - the scarf over the head and neck and the most widely accepted form of modesty in the Islamic culture.
The scarf or Hijab around the neck and face is the "most popular" choice. However, some women do wear the chandor - which is the "cape" we see many times here in the US.
There is debate about whether or not the Hijab is required to be worn in the Quaran. However, the point is that the women, when seen in public, should be NON-Descript. The man who marries her is the one who should see her beauty. The burqa is NOT worn by females until they reach womanhood, most usually wear the scarves or Hijab but NOT the burqa. When they are in their private residence, they typically do NOT wear the attire.
Under Taliban rule - women are NOT allowed to study or work. If they didn't wear the burqa, they were considered unfit for marriage.
Hope this helps!