One will notice the difference between a Cree torchlight and a normal LED torchlight. The Cree torchlight does not use a normal LED, but rather uses a chip when you look at it (never look into it when it's on). There is a circuit board with a small square chip that powered the light.
Cree is actually a company that manufactures a number of different models of high output LED's that are widely used in torchlights. They do not actually make torchlights, though some companies will describe their product as a "Cree torchlight" but actually this refers to the LED inside the flashlight. So Cree Torchlight is also a type of LED torchlight.
You may wish to read more details on Cree here. You may find some Cree jargons that look confusing to you when you are buying a Cree torchlight. In simplicity, here are some clues.
XML, XP-E, XR-E, XP-G, etc are cree LED types - which mean they all have a different size LED "Bulb" and the bigger, the more Power (but throw can be Less) and the beam will be slightly different.
Q2, Q3, Q4, Q5, R2, R3, R4, R5, S2,T2, T3, T4, T5, T6, U2 - these are called Bins and basically the higher the Number the more Brightness (and I assume more heat build up).
XR-C/XP-C. The C means Not So Good. Avoid
XR-E. Formerly the mainstream Cree product - at least for use in torches. Notorious for its "Cree Rings" probably caused by the metal ring around the emitting die. Still the best for devices wanting a lot of throw. Have been driven at silly current with a great deal of success.
XP-G. Current mainstream device. More efficient than the XR-E but a larger emitting area so needs a bigger reflector to get the same throw as an XR-E.
XP-E. Essentially similar to the XP-G but designed for a lower current (Its maximum is 1A, the XP-G can handle 1.5A)
MC-E. Basically 4 XR-E dies in a single package. Useful for flood type lights and where you need silly amounts of light.
When buying a Cree torchlight online, make sure the supplier shows the Cree LED photo so that you know you are not buying a traditional LED type of torch.
I personally find that most Cree torchlight looks brighter when run by rechargeable Li-Ion batteries like 18650 Li-Ion compared to AAA or AA types of batteries. Read up on the safety aspect of using Li-Ion batteries on Cree torchilight. Also Cree torchlight tends to heat up more than traditional LED, so be careful when using a Cree torchlight.
So how do we buy Cree torchlight? Sometimes excessive pursuit of brightness or lumens is a waste of money without taking into consideration whether it is used at home or outdoor. I find Cree torch is extremely bright for close jobs range and a traditional LED torch is more suitable in this case.
So for normal home, mounted on bike or outdoor use, 200 to 300 lumens are good enough. 500 to 600 lumens are you to throw a long range. Even a less than 200 lumens Cree torchlight can meet daily use, especillay if it is a Cree Q5 LED.
In summary, here are what you should look at;
Bins - The bins refer to the grading system used with cree LED hand torches to measure brightness or lighting efficiency, tint and several other variables. To date, the highest standard is the Q5, followed by the R2 for the Cree brand. For Seoul, a good series to look for is the P4. If you prefer a certain tint in your lighting, you might also want to check out the related bin codes for this variable.
Lumens - A lumen is a standard measure of luminosity that a hand torch is capable of producing within a specific area or space. The higher the lumen figure, the brighter the torch is.
Mode - The mode refers to the types of lighting that the LED hand torch is capable of producing. Two-mode switches usually mean the torch can create high and low beams. A four-mode switch usually includes a high and low beam, a slow strobe and a fast strobe. Which mode you choose will depend on your foreseen use.
Body - There's plastic and then there's metal. Plastic is decent enough and should last as long as your cree LED emitter works, but it can produce static and thus attract dust. It will also scratch. If you will be using your hand torch in rough and ready situations, go for a solid, scratch-proof body.
Here is a video on how bright a 250 lumens R2 Cree torchlight;
Another video using a 1000 lumens Cree XML T6 torchlight;