I think the answer lies somewhere in the different approach of the different LED bulb manufacturing methods out there.
phillips uses a straight blueish white LED with no phosphor coating on the LED lens. This throws a lot of lumens per watt. it then creates a bulb using a plastic "filter" of yellow with a tinge of green to take the blue colored LED to a warmer white. the bulb looks yellow, turn on the power, it looks white. but the yellow absorbes many of the lumens per watt gained.
other manu's seem to be going the other route- take a warm to cool white LED from the factory that has a yellow green phosphor over the LED lens, and then use frosted white for the plastic "filter". the bulb thus looks "normal colored" when off. you sacrifice some lumens per watt on the phosphor, but don't lose so many through a frosted glass or plastic cover.
which is right? time will tell which will give you a better color and efficiency. my guess is both phosphor and yellowed colored plastic will fade over time. and these bulbs are rated to last a LONG time. so a bulb with a color temperature of 2700k today might be somewhat different at 10,000 hours or 30,000 hours. again, time will tell and we will learn as we go. it took decades of improvement to get the incan, halogen, fluorescent, HPS and Metal halide where they are to today.