You may not know it, Kayelle, but you've just touched one of the raging controversies in the culinary world. To wit: Just what is spatchcocking.
Most Americans, if they even know the word spatchcock, use it inter-changeably with butterfly. In general, however, we say butterfly and the Brits say spatchcock.
However, there is also a technical difference between them. If you merely cut away the backbone and open the bird like a book, you have butterflied it. To spatchcock you have to go further, and remove all the rib bones as well; a step most of us do not take.