Why is there "Load Driver" during Windows installation?

When installing windows, there's a link to "Load Driver" as shown:

From what I know, drivers can always be installed after the OS is installed, so it seems odd that there's a "Load Driver" link during Windows installation.

What kind of "drivers" are they talking about? Is there any difference installing these drivers after Windows is installed?

This is what I see when I click on the "Load Driver" link:

^{**these images are found on the web (thus the unmatching backgrounds) since I can't screenshot on my PC while installing}

Solution 1:

Lets say you have a raid controller with disks you want to be accessible during installation. "Load driver" can be used to load the controller driver before installation.

Edit: Some might also say that it's a leftover from Windows 2000 / XP and before :)

Solution 2:

At this point in the installation process, you're referring to any driver that would be required to access a storage device (used as the installation target) that isn't currently accessible.

Usually, these would be SATA/SAS/IDE/SCSI controllers. But it could also be some fancy PCIe storage device that Windows Setup simply can't access.

Drivers for non-storage devices are usually completely irrelevant at this point. Although loading certain network adapter drivers could be required in some cases (although I have never seen that personally).

This is the screen you will see if Windows Setup was unable to detect any storage devices:

Loading any other drivers won't make any difference in comparison to installing them later on. In fact, I wouldn't even consider this to be a proper installation of those drivers. This part is probably just taking care of the bare minimum to get the device working right now during the setup and the next boot.