Don't worry, this article will clearly define the differences between these three knife designs.
The paring and utility knives have a European origin, whereas the petty knife come from the Japanese tradition. Paring knives are easy to classify, having had a long and stable place in the kitchen cutlery lineup. The other two are not so easy to define. The line blurs between the classic Western utility knife and the Japanese Petty. So first, let's get the easy one out of the way.
The paring knife is the perfect compliment to larger knives in the kitchen. It's small, pointed tip can do all of the fine and delicate work that a chef's knife can't do, like mincing small vegetables and herbs, taking strawberry tops, and doing decorative work with the blade tip. It also works as an 19th century peeler for things like cocktail citrus and baking apples.
The main attribute that separates the Western paring from the other two is its short and narrow blade profile. Notice how the paring blade doesn't really protrude beyond the width of the handle (Fig. 1). It's impossible not to hit your knuckles if attempting to use this knife to chop on a cutting board. Instead, come at tasks on the cutting board from a 20-40 degree angle, using the last inch of the blade-tip for piercing and cutting.
There are a few variations on the basic paring knife, involving specialized blade profiles like "the sheep's foot" and "bird's beak". But all of the paring knife styles fit this basic niche for small and delicate work. It is an essential knife to have in the kitchen.
Now on to the more complicated definitions of the Western kitchen utility and the Japanese petty.
Some say the petty is a Japanese utility knife. Others say the Western Utility sits in between the paring and petty in terms of size and tasks. Based on the knife options available today, those general statements do hold true-- just not to the original intention of the old knife makers centuries past.
The Western kitchen utility knife, in its traditional form could be described as an elongated paring knife: Same overall blade height and thickness, but with 2+ more inches on the business end.
In its early form, the kitchen utility was just a small, all-purpose knife to have around the house. It was used for small game processing --not unlike the famed bird-and-trout knife-- as well as whatever general tasks the knife could handle. In the early days, the variety of kitchen knife designs and accessibility of knives in general limited what people used regularly. So the utility knife really did honor its name.
Over time, however, The Western kitchen utility has moved into a kitchen role more exclusively and Its design has expanded, sometimes looking more like that of the Japanese petty knife. Specifically in terms of blade height, allowing the fingers to sit above the cutting board when doing chopping cuts like a chef's knife-- something that a paring or traditional kitchen utility knife's anatomy won't allow for.
So what are the differences between the kitchen utility and the petty?
In the modern context they are almost interchangeable, the knives sit at two poles on an ever-overlapping spectrum of design. The origin of the traditional styles, and the names themselves separate the two knives. But in a modern, practical context one might just say the Western kitchen utility and the Japanese petty occupy the same role. Some cooks prefer one design over the other, but rarely would they bother having both, taking up the precious real-estate in one's knife collection.
Bottom Line: Which one?
The utility has a narrower blade, better suited to tasks that involve curved cuts with the knife above the cutting board. butchering a chicken or peeling fruits like one would with a paring knife.
The petty has a taller blade, better suited for use on a cutting board with chopping motions due to the added room the taller blade makes for your fingers.
Japanese foods, ingredients, and cooking styles differ from traditional Western cooking, defining the development of these blade designs. Both these knives, while occupying a similar space, focus on a different style of cooking. So it comes down to cooking style and general preference.
A wrench in the knife roll: An introduction to the mini-chef's knife
Another interesting variable in the Western kitchen knife nomenclature is a knife that looks like a mix between a petty and a chef's knife that is often called a kitchen utility. It has more of the blade height and handle size of a chef, while having a more moderate blade length. A great knife, but hardly holding true to the design origins of the Western utility. I believe this knife design is a derivative of the common Japanese kitchen knife called a santoku, which is basically a shortened chef's knife. So, for Western knives, the term "mini-chef" fits just fine.
Here are all four kitchen knives in a lineup, Redroot style
Redroot Blades focuses on Western style kitchen blades, yet we have both petty and mini-chef knives available with the Western paring knife. Check out the Western Kitchen Knife Collection for our products, as well as the Western Kitchen Design principles article for more theory behind the design.