The technology for white LEDs is evolving quickly. Recent developments in highly efficient phosphor coatings are allowing manufacturers to create white LEDs with smaller die sizes and higher Lumens per Watt, in other words you have smaller and brighter lights.
One way to calculate different model LEDs is to calculate the Lumens/Watt. LED output is measured in “Lumens,” which is the total luminous power emitted from the light source. If you divide the total Lumen output of a light by the power draw of the light, you will get the Lumens/Watt. A high lumens/watt number means that you will get a brighter light for the draw. For example, the older 10watt Cree MCE and Seoul semiconductor P7 LEDs are rated at 75 lumens/watt. Contrast with the 5watt Cree XPG LEDs that produce greater than 100 lumens/watt or the latest 5watt Cree XML that produces 140 lumens/watt and you can see why newer LED lights are brighter/ more efficient.
Of equal importance, all LED models have a die size or footprint. The smaller the LED die(“bulb”) the easier it is to create the reflector and optics that put the light where it is needed the most. For example, the older 10watt Cree MCE and Seoul semiconductor p7 LED(long name:)) dies are very large which makes it virtually impossible to focus the light without wasting a significant portion of the light. The result is a dimmer and less efficient light for the power draw. On the other hand, the 5watt Cree XPG die is 85% smaller which allows for almost completely efficient use of the available light. This also allows the reflector to be half the size resulting in a much smaller overall lamp size.
Baja Designs is always researching emerging light technologies and maintains close relationships with LED manufacturers; BD is often one of the first companies to get new LED prototypes to test.