Why I call them bunnies and not rabbits
Rabbits are bigger. Even SweetPea, who tops out about 7 pounds now (huge next to her 2- to 4-pound siblings), is a bunny. The big 'uns are like Flemish Giants. They're rabbits. Mr. or Mrs. Rabbit if you don't want them to sit on you. The little guys are just bunnies.
However, when I talk to non-bunny people, I make sure to specify "house rabbits" to emphasize the indoor quality of their domicile.
Do you call your house rabbits "bunnies" or "rabbits"?