Are the cells within an organism the same If not how can they differ?

No, the cells within an organism are not all the same; they can differ significantly in structure and function. These differences arise from the specific genes that are expressed in each cell type, which in turn influence their shape, size, and role in the organism. For example, muscle cells are adapted for contraction, while nerve cells are specialized for signal transmission. This specialization allows for the diverse functions necessary for an organism's survival and development.