A topic that crops up in conversation every now and then is ‘when does a bird have a beak and when is it more apt to call it a bill?’ One would think it is clear: a Village Weaver has a beak and a Spoonbill obviously has a bill! What is the distinction then?
I can no longer recall from where I noted this information, but according to this source beak is the general term applicable to all birds, although it usually refers to raptors, and when striking or pecking is in question. The terms beak and bill are often used interchangeably for crows, finches, and sparrows. Bill on the other hand is almost exclusively used for sunbirds, pigeons, waders, and web-footed birds. There does not appear to be an official difference and it seems that these terms are synonymous; their use might according to personal preference.
Trevor Carnaby in his very useful book, Beating about the bush: Birds, describes a variety of shapes of beaks that are adapted according to the feeding requirements of the different species of birds. There is an interesting discussion on this topic at https://ww2.rspb.org.uk/community/ourwork/b/natureshomemagazine/archive/2017/08/24/beak-or-bill.aspx
What do you think?