The Chinese manufacturers often inflate their lumens claim. In the case of the UF-900 light, it is possible to get 900 lumens by using five (5) Cree XR-E Q5 bin LEDs installed in the flashlight. But this light has poor throw because of compromises made to the reflector to fit the 5 LEDs. It splashes a flood of 900 lumens everywhere. A single Cree XR-E Q5 bin LED installed in the UF-900 flashlight body with a smooth reflector, will only have about 200 lumens but throws very well.
E-bay has lots of UF-900 lights for sale that have the 5 LEDs installed in them.
The SST-50 style of LED is capable of more lumens (and higher battery drain) than the XR-E style. But the SST-50 doesn't throw as well as the XR-E (because the SST-50 LED die size is large compared to the XR-E - smaller is better for throw). The UF-1500 flashlight link states that the light produces 1250 lumens with an LED current flow of 3000 mA. Looking at the Luminus LED manufacturer's specs, the best SST-50 quality bin can only produce 850 lumens at 3000 mA. The SST-50 LED is made by Luminus (not Cree, as the advertisement claimed).
The HS-802 light uses the XR-E LED, R2 bin. The R2 quality bin is slightly better in performance than the XR-E Q5 bin (when the LED is driven to the same current flow).