Well most Pagans today are famillar with the term and concept of a Book of Shadows, infact many of you probaly have one of your very own, but another term of which you might not be as famillar and perhaps is not as common a concept is the grimoire, and it can be difficult to distingusih the differece between the two, though thier are a few things which set the two distinctly apart, they both can be vaulauble and useful tools for your practice.
The Book of Shadows can best be seen as a Pagans or Witch's Diary, it is where one recourds a vast arrwry of different subjects reguarinds ones practice, personal thoughts upon subjects, epxeirinces, spells, rituals, and so forth. It is really whatever you so wish it to be.
A Grimorie on the other is a bit more rigid than that, a grimoire is more scientific for lack of a better word. It is used explcicitly for documenting spells with detailed fomurlas upon how each spell is to be worked and preformed including all tools to be used when the spell is best preformed, and so forth, but it is abscent of any personal thoughts.