Is all ddr4 so dimm ram the same?

The board has two sodimm slots but it will only boot up with one stick of ram This begs the question though, if it only supports one dimm why

Standard DDR4 operating voltage is but XMP enabled SODIMM requires higher voltage, eg Also some laptop manufacturers lower voltage

ddr4 sodimm slot slot capacity) by electrically buffering the signals at a cost of an Module packaging edit A 16GB DDR4 SO-DIMM module by Micron DDR4 memory

ddr4 slot vs ddr5 Connectors Memory Connectors Memory Socket Connectors DIMM Connectors · Number DIMM Connectors DDR4 SODIMM 260P STD TE Connectivity Alcoswitch