Question

If every cell contains identical genetic instructions, how do cells develop differently
from one another?

Answer 1

I'm not sure they have identical genetic instructions? One thing would be their shape and functions. ie. mature red blood cells lack nucleus.
Also different cells in different parts of your body have different things. I think your liver cells are have more of smooth endoplasmic reticulum compared to the other parts of your body. Also, your muscle cells should have more mitochondria to produce more energy.

Answer 2

Thanks, but I found the answer later. It's gene regulation
All cells have the 48 DNA chromosomes. BUt through gene regulation, some are expressed or turned off.. So all cells contain the DNA, but cuz some are turned on (the genes) or off, the cells are different

Answer 3

cool :D