(Work in Progress)
For keyboards, there are various lighting options available, and the different types of lighting can be difficult to understand. Hopefully, this will clear it up for you.
There are a few different factors for lighting:
Single-color vs. RGB
Group control vs. Individual control
North-facing vs. South-facing switches
First, you can have light pointing in various directions. Here are the different options for that:
In-Switch - An LED is placed inside or through the switch housing and faces upward
Indicator light - An LED is placed somewhere on the board, not on a switch. Examples: Num lock indicator
Underglow - LED is pointing down towards the bottom of the keyboard
An LED can be a single-color that can't be changed or an RGB LED that can change to a specific color that can be controlled.