Laptop memory modules are not universally compatible across all brands and models solely based on form factor. While the physical size determined by the form factor (such as SO-DIMM) plays a role in compatibility, other factors like the memory technology (DDR3, DDR4, etc.), speed, voltage, and the laptop's motherboard chipset also determine compatibility. These specifications must match for the memory to be compatible and function properly in the laptop. Simply matching the form factor without considering these other elements may lead to incompatibility issues.