There are many types of beads that have very similar characteristics. The AB (aurora borealis), the Vitrail, and the Iris bead are three of those types.
AB beads have a sprayed-on silver/iridescent coating that is generally metallic. The coating may reflect a wide array of colors, but generally AB beads have a silver coating that covers part of the bead, but not necessarily the entire bead.
Vitrail beads are also metallic, but the finish is fired onto the bead instead of sprayed, making it more permanent. The coating is generally only on part of the bead, which is similar to the AB bead, but where AB beads have a silver coat, vitrail beads come in a variety of colors. Vitrail coatings are most often found on faceted beads.
Iris beads are very similar to vitrail beads, but the coating typically covers the entire bead instead of just part.