The difference is in the efficiency of some of the newer LEDs. Most COBs are garbage (unless you go with high end ones like Timber sells). The 480W of Samsung strips I run in my 4x4 have been getting me more than double the yield I was able to get from running 600W of COBs.
Timber is using the same parts that most everyone is using. People don't really understand lights and it's really taxing to try and explain. Majority of COBs made can handle 2.1 amps of driver power. That means your typical 50 volt cob can push over a 100 watts of light.
The newer leds are more efficient but your talking baby steps and again efficiency only matters at the meter. The biggest problem with led and has been is shipping issues. They cannot build a light to cover huge footprints that will easily go in a box. So they drive the diodes a little harder to reduce the size of the light. The softer you can run a diode the more efficient.
The amperage of the driver is your accelerater BUT drivers cost money. The harder you drive the diodes the more drivers you need. It all.adds up. I'm currently running 15 COBs @1400 mA
If I need more light all I have to do is swap to 1750, or 2100. I can increase the par by triple but the plants will never see it. With LED 40 watts per square foot has always been the rule. Maybe with newer diodes now you can get away with 35 but I doubt they have really come that much further. A watt of electricity still produces 3.5 BTU of heat no matter what the fuk you have plugged in.