How does differentiation lead to tissues in the developing organism

The structures of the body or the set organ relates to its function by the cell that form the organ. In a cellular level, cells makes up the tissues which make up the organ then the organ system. Focusing in organs, these organs functions accordingly as what they're supposed to do and was formed to such degree to ensure its optimum performance for example, the skin is made up of epithelial tissues which has seven layers which serves as a protective layer of the body. Another is the brain, the brain is made up of many nerve tissues and cells that allows it to do its responsibility or acted function, since nerve cells are the cells responsible for functions like sensitivity, reaction, emotion, memory, sensation & perception and etc the brain is made from brain cells, itself.