The difference is the number of transistors.
The height of the cpu nanometer refers to the gate width of the silicon transistor, the smaller the gate width, the larger the number of transistors, so the stronger the computing power. For example, a 7-nanometer cpu has 96 million silicon transistors per square millimeter, while a 4-nanometer cpu has 170 million transistors per square millimeter. The computing power of a 4-nanometer cpu is much higher than that of a 7-nanometer CPU.
The lower the nanometer, the more advanced the process, the lower the energy consumption, and the more new the technology.