'Bitcoin' (with a capital B) usually refers to the protocol, whereas 'bitcoin' refers to the currency. It should be specified at the beginning that the book doesn't follow this convention.
Hey, that's a great point! The BRAIINS convention is to use a little b everywhere and by way of the curse of knowledge, we forgot to mention it in this book!
'Bitcoin' (with a capital B) usually refers to the protocol, whereas 'bitcoin' refers to the currency. It should be specified at the beginning that the book doesn't follow this convention.