Watts is unit for energy consumption whereas Lumen (luminous flux) is the light output/brightness of a lamp.
Generally higher wattage/energy consumption of a lamp implies higher lumen output.
Today people are moving from traditional GLS Lamps and Flourescent Tubelights to CFLs and LEDs.
In the 2000s, people first switched from traditional incandescent bulbs to CFLs or compact fluorescent lamps which offered same light output at 1/4th of power consumption. So we could replace a 60W GLS Lamp with a 15W CFL. Now we are moving from CFL to LEDs, which offer further 50% energy reduction. Hence 15W CFL can be replaced with an 8W LED lamp.
Lamps today have become more energy-efficient, which implies they give more light output (lumen) per watt.
LED lamps that 3-4 years ago used to be 30-40 lumens per watt, are now touching more than 100 lumens per watt and in labs, 200+ lumens/watt have been achieved. Hence in coming years, you will see brighter lamps consuming lesser power, which means less CO2 emissions and hence contributing to environment improvement.
In layman terms:
100W GLS Lamp (Life 1000-2000 hours) has been replaced by 25W CFL (Life 5000 hours); which in turn is being replaced by 12W LED (Life 50,000 hours).
How does this translate into money-saving. We will explain this next week.