Bonnie has the appearance of a large purple rabbit. He has a red bowtie, and carries a guitar onstage.
In the second game, his overall appearance is unchanged, but his suit has been heavily disheveled. Most noticeably, his face has been gutted, revealing the animatronic endoskeleton underneath. His entire left arm is missing, as well as several other patches on his suit. He retains his bowtie, and also has 2 buttons lined up underneath it.
In the first game, Bonnie starts out on the Show Stage, with Chica and Freddy. He is typically the first of them to move, and for the first three nights, is the most active of them all. He always approaches from the West Hall (the left side), and appears to have the ability to teleport to any location in the building.
In the second game, Bonnie starts out in the Parts/Services room, along with his "old" counterparts. He will makes his way into the players office, either from the door or from the left vent, similar to his behavior in the first game.
In Five Nights at Freddy's 2, all of the original animatronics are "replaced" by newer models.
Toy Bonnie appears dramatically different to his counterpart in the original game. Toy Bonnie is very light blue in color, and his suit appears to be made of porcelain, rather than cloth. He has big green eyes, and wears a red bowtie. He also carries a guitar onstage and in Party Room 2.
Like all of the "Toy" animatronics, Toy Bonnie has rosy cheeks, as if they are blushed.
Toy Bonnie starts off on the Show Stage, along with the Toy models of Freddy and Chica. Like the original Bonnie, Toy Bonnie is the first one to leave. He will approach from the right vent to try to get into the office.