I have two lamps
6W LED(OSRAM 50R): equiv 40W or 170 lm
15W WW827 Tornado Philips, equiv 85W or 950 lumen
Why the 2x power difference and 6x luminosity difference?
There are a couple terms involved that all have specific meanings:
There's not a direct relationship between watts and lumens, but you can look at the luminous efficiency to compare bulbs. Wikipedia lists values for common household bulb types:
The LED you list has an efficiency of 28 lumens / watt, which is pretty poor for an LED. LEDs have been increasing in their efficiency; maybe it's an older model? Your CFL is 63 lumens / watt, which is pretty good for a CFL.
Compare those to the current gold standard for mass-market LED bulbs, Philips' L-prize LED, which puts out 940 lumens using 10 watts, or 94 lumens / watt.
You're also seeing the problem with "equivalent watts", which is kind of an unhelpful metric. I don't know if there's any regulation on what manufacturers can claim as the incandescent equivalent, but I've seen bulbs as low as 700 lumens and as high as 950 lumens all claim to be "60 watt equivalent". Even among incandescents there's a range of light output for a specific wattage. The most reliable way to look at brightness is the "lumens" rating. If you're trying to match the brightness of an existing bulb, try to look it up online to find the lumens.
So, when we rise power two times, luminosity increases 6 times. This is my speculation. But it cannot be a good answer because, as we see for powers > 100 W, 2x power increase adds only 1% to the efficiency, not 300% as needed for 6x.
Lumens is the absolute amount of light that a bulb puts out. You can use this to accurately compare how bright two bulbs will be. The one with the higher lumens value is the brighter light.
However, most people have no idea how bright a 170 lumen or a 950 lumen bulb is. What they do have is experience of how bright a 40W or 85W incandescent light is.
By using the "equivalent watts" value bulb manufacturers are making it easy for the typical shopper to have the information they require in order to make an informed decision over which bulb to buy. However, as Henry Jackson points out this is usually a figure calculated (or even made up) by the manufacturer and should always be treated with some caution.
I would assume that each manufacturer has measured the light output from a "standard" incandescent bulb (or a number of bulbs) and used that lumen value to calculate the "equivalent watts" of their bulbs.
Once incandescent bulbs have been completed phased out and/or more different bulb types are on the market you might see a switch to using the lumens value exclusively as this becomes more widespread and accepted.