Help me explain: what do the bull's head, dog's head and hood of SLR cameras mean?

The hood refers to the lens that comes with the purchase machine. SLR cameras are sold in two packages. One is that there is only one fuselage, and the packaging sells only one fuselage, excluding the lens. This kind of buyers are mainly people who already have a variety of lenses or have higher requirements for lenses. The other is a set product, which contains not only the camera body, but also one or more lenses. This is the manufacturer's packaging and sales for the convenience of novices. It is usually much lower than buying the same lens+camera body. In fact, the dog head is similar to the hood, mainly referring to the lower lens configuration under the same brand. Usually these lenses are arranged in the middle or low-end machines. Of course, not all of them. Although some of them are sets of cameras, they are still excellent lenses. Of course, the lenses in the high-end kit are all better lenses. It can't be said that all the shots in the set are dog heads, but it can be said that.