Transistor density is different.
The biggest difference between the chip 3 nm and 8 nm is the difference in transistor density. The nanometer is a unit of physical length that represents the gate width of the transistor, so the smaller the value, the more silicon transistors per unit area. So the 3-nanometer transistor density is about 250 million per square millimeter, while the 8-nanometer chip transistor density is about 60 million per square millimeter.