As I have already mentioned, baby body wash and shampoo are two different products. The shampoo is used to wash the baby's hair, whereas body wash is used to clean the body.
These products are intended to be used separately, but many manufacturers offer multifunctional baby wash and shampoo options that you can apply on the baby from top to toes. Such a product can save you money and space in a bathroom drawer. In all cases, you should check the instructions carefully before applying any of the products you buy.