First, there are absolutely different kinds of stem cells. At the moment of fertilization, what’s known as a totipotent stem cell is created. A totipotent stem cell can differentiate into any cell type in the body, and go on to create an entire living, breathing organism. In the case of a human being, it creates a newborn baby.
But to answer the question, yes, stem cells can also be specialized. They can be developed partially. They can be developed into what are called hematopoietic stem cells. Those are stem cells that give rise to the blood and immune system. Those are the kinds of cells that are found in bone marrow or are found leftover in umbilical cord blood.
They can also be pre-programmed to drive down one part of what we call the tissue lineages. Our body is made up of many different mature cell types, specialized in different tissue lineages. Those lineages are called endoderm, ectoderm, and mesoderm. For example, endoderm tissue goes on to create respiratory organs among others, ectoderm forms skin and the nervous system, and mesodermal tissue goes on to create things like bone and cartilage and muscle.
The very nature of a stem cell means that it has a degree of versatility in how it can mature and specialize. But the fact is that there are also different categories and different types of stem cells, each having a certain degree of specialization.