We artists are not very interested in nomenclature, it seems. We talk about painting with palette knives, but really, palette knives and painting knives are two different creatures.
A palette knife is blunt, with no sharp edge. It's used for mixing paint colors, mediums, etc. directly on the palette. The palette knife is symmetric and often has either slight crank between the handle and the blade, or none at all. I have discovered that the plastic ones break easily.
Painting knives, on the other hand, usually have a large crank, to keep the artist's hand off the paint surface (in theory, says the messy artist). Painting knives come in an unbelievable variety of styles, shapes, and sizes.