Fillet Knives vs Boning Knives
Fillet Knives and Boning Knives are really quite similar. Both knives tend to measure around six to eight inches in length and both have narrow blades which have an upward curve towards the tip. The main difference is that fillet knives tend to be much more flexible than boning knives although you can purchase stiff fillet knives and also flexible boning knives.
The flex of a Fillet Knife should allow you to easily glide the blade accross a fishes bone to remove the flesh leaving little waste. The Boning Knife on the other hand is considered more useful for trimming a tenderloin or boning a eg of lamb.
The Boning knife is generally thought to be a speciality knife with very few alternative uses. Most home kitchens will not have one although they can be invaluable if you frequently bone whole chickens or trimming silverskin. The Boning Knife has a tapered tip which assists in seperating the meat from the bone whilst avoiding puncturing flesh.