The different types of ddr modules are easily identifiable because of what factor?

Physical aspects:

DDR - 184 Pins;

DDR2 - 240 Pins;

DDR3 - 240 Pins;

DDR4 - 288 Pins;

Explanation:

    The modules for each generation of DDR memory are physically different which does not allow the installation of a DDR2 or DDR3 module in a socket designed for DDR4, for example. Unless the motherboard has both DDR2, DDR3 and DDR4 sockets at the same time, only some models released in technology transaction periods support both types.