do they only affect the individual keycaps or the profile of the whole board? like let’s say oem are sharp and XDA are rounded, but is there a difference between the height of the rows?
Check out the site https://www.keycaps.info/ it shows side profiles and keycap heights of common profiles.
You might have seen this image (or similar):
The normal keyboard should have a flat PCB and the variation in height entirely based on the cap profile. Some profiles will have interchangeable keys, e.g. XDA you can swap the keys to any row except the first row while OEM you can’t really swap keys between rows or they’ll stick out.
As far as I know, you can use any profile on any board (provided the keycaps are compatible with the switch stems).
Hopefully that helps answer your question.
