Why might adults and children have different kinds of marrow?

There is no difference in the type of bone marrow between adults and children. Both adults and children have red bone marrow, which is responsible for producing blood cells, and yellow bone marrow, which is primarily composed of fat cells. The composition of bone marrow can change over the course of a person's life, with children having a higher proportion of red bone marrow than adults. However, the type of bone marrow remains the same.