Bonus Levels

Did you mean Exclusive Levels? Not to be Confused with Bonus

Bonus Levels is the original episode in Angry Birds Trilogy. In the episode, six levels are in both Angry Birds Classic and Angry Birds Rio but in Angry Birds Seasons there are seven levels.

Gameplay
This episode is designed for challenging/Pro players of the game, the levels are huge and providing you 3-Stars because of the massive amount of destruction you can do to the towers.

Every Bird (Except for Bubbles and Stella) are playable in this Episode.

Also in The Levels they follow there corresponding order, Angry Birds Rio being in from Smugglers' Den to Smugglers' Plane, and in Angry Birds Seasons it goes from Trick or Treat to Moon Festival but in Angry Birds Classic it not in order by it’s original Levels.

Trivia

 * This episode is not available on 3DS and PSP Editions of Angry Birds Trilogy.
 * Red only appears in Bonus 3-1.