3000K is "warmer" than 4000k. Think the difference between a lower wattage incandescent light compared to a cool white or daylight fluorescent bulb. A light that is 3000K will appear yellow compared to a higher temperature bulb. True daylight is in the 5000-6000 range. To see the different light temperatures, try the local Lowe's or Home Depot. Our local Lowe's has a display with the different temperatures side by side.