Dear 100 Hour Board,
What is the scientific difference between a beak and a bill? Is there an official difference? If not, what is the unofficial difference? My preliminary google searches didn't give me anything definitive.
If by scientific you mean ornithological, the OED has your back. Here's what it says about the usage of beak vs. bill:
In Ornithology, beak is the general term applicable to all birds; in ordinary language beak is always used of birds of prey, and generally when striking or pecking is in question; beak and bill are both used of crows, finches, sparrows, perching birds and songsters generally, bill being however more frequent; bill is almost exclusively used of humming-birds, pigeons, waders, and web-footed birds.
There appears to be only an unofficial difference. It's easier to think of as a visual: