LED light bars have different colour light output depending on the make and model. The colour is called 'temperature' and is measured in Kelvin (or K).
The higher the temperature, the brighter and whiter the light will be. Each manufacturer has different recommended temperatures for different types of applications. Most manufacturers use a temperature of around 5500K for a general-purpose light bar.
'Colder' or bluer lights are more unnatural for the human eye. LEDs naturally tend to be a colder colour, so it harder to produce warmer colours. For this reason, most cheaper LED products use a cooler colour temperature. However, some higher quality products can achieve a natural warm colour by using a higher powered LED combined with a special phosphor coating on the lens of the lamp. These higher quality LED lamps provide a more pleasant and natural looking light but may be more expensive to buy.
Cooler whites are usually over 6000K, which is a clear white light. They provide good visibility but do not project a nice natural colour like lower temperature bulbs.
More natural warm colours are between 4500-6000K. They produce a more pleasing white light that is very similar to natural light from the sun, making them a good choice for night driving. This temperature will put a lot less strain on the eyes, making them a more comfortable option for night time driving. See the below example in the STEDI Type-X Pro Spot Lights.