Pieds have more white areas than IB's that only have white on their faces. A dark pied will have some white flight feathers and usually some white on the throat area like the peacock in the far left.
Pied Peahen
Dark pied (only white on upper neck and some white or frosted white flight feathers)
Pied peacock
Pied is a pattern. You can have pied peafowl in different colors like purple pieds, peach pieds, etc. There are over 225 varieties of peafowl. You might want to check out Legg's peafowl to see photos of most of the varities: http://www.leggspeafowl.com/photogal.htm
Pied peafowl are very unique because no two are alike. They all have their own different white markings.