"Warm white" bulbs are generally considered below 3000K (3000 Kelvin). Correlated Color Temperature (CCT) in lighting describes the color that light appears from a lamp, measured in Kelvin (K).
It's important to note that color temperature does not describe the actual temperature of the lamp itself but the color it produces, which is counterintuitive; the higher the color temperature, the "colder" the light will appear.
Warm white is around 3000 Kelvin and is a pale yellow, similar to a traditional incandescent or halogen light, while cool white is on its side, 5000 to 6000 Kelvin, a bluish shade, more like you get from Neon.
Warm white is usually the lower number in the Kelvin spectrum, usually 2,700 to 3,000 Kelvin, meaning the light will have a warmer, more yellow tint, which gives a warm and cozy atmosphere. Such bulbs are usually better suited for living rooms, dens and bedrooms. While soft white is usually a little higher on the spectrum, at 3000-4000 Calvin, a whiter light, this bulb is more suitable for kitchens and bathrooms.
Where is the best place to use warm white lighting?
For the living room, dining room, bedroom or any other room that needs soft lighting, using warm white light is more relaxing for the eyes, and in warm white light, the skin appears softer, which is also beneficial for portrait photography.