Would it be alright to mention which AliExpress store it’s from?
Are the capacities identical?
For that matter Keeppower is a knock off brand. KP doesn’t manufacture cells, they buy them, re-wrap them, add protection circuits, and print labels to label them.
I’d say the are legit. Or as legit as can be. Efest, EVVA, Orbtronic, etc… are all re-wrap companies.
Yes I know they don't, but I doubt they are going to sell them with fake CE RoHS text on the label. Maybe I could be wrong, but I clearly remember reading if the C and E are too far apart on any product with a label like that, then they are 100% fake, no questions asked.
Fake is a relative term in China… lol
C and E has to be far apart in a real CE logo. If you make the C into a circle the line has to exactly overlay the back of the E.
I.e. the Aliexpress version looks like the correct CE logo.
That means I have it backwards then 
Many companies uses a wrong CE logo, even European ones. It do not necessary mean the product is fake or not CE “approved”*.
*CE is not a approval, but sign from the manufacturer that says they are following the CE requirements.
Hmmm… I happen to have a BLF Q8 sitting next to the computer. Looking at the tail cap - it has the fake incorrect “CE” marking. :person_facepalming:
But it is odd that a single manufacture (KeepPower) would use both correct and incorrect marking on their product.
I also see that the Illumn cell has 2 symbols after the “RoHS” and the ALIX cell has 3 symbols.
The label is probably designed by some marketing people that do not know the rules on how a CE mark must look. A new version may be corrected because somebody that do know told them to fix it.
But next time a new designer is making the label, the problem may be back.
My Keeppower batteries has the “China Export” marking
http://www.cemarkingassociation.co.uk/ce-marking-and-the-chinese-export-logo/
I am not a battery expert but I would say they are both “real” Keeppower batteries, the only difference is that the ALIX cell is the newest with the 3 symbols after the “RoHS and the correct CE mark.
Inside EU there is no legal China Export mark, it is a wrongly designed CE mark (The rules says something about it being illegal to use marks that can be confused with CE marks).
Are there any differences in weight between the two batteries?
Good thought. The Aliexpress one weights 6 gram more at 222 gram vs 216 gram for the illumn one.
It almost sounds like the fake is the illumn one.
BTW, are you sure about those weights? 200 grams is way too heavy for a 26650. Maybe they’re both fakes, and filled with iron!
They might just be different batches. Keeppower are known to change specifications and cells wrapped over time, just like Efest. In fact I’m aware of 4 different versions of the protected 5200mAh battery - longer, shorter, non raised top, and higher current protection.
Had to pull out my magnifying glass as it's a small digital scale but it was set to pounds first time around and was .222 lbs. etc not grams. Time to get reading glasses I would say. Just weighed them all in grams now and here are the results as I got them in pairs from ali and illumn.
AliExpress
1 - 101 grams
2 - 99 grams
Illumn
1 - 96 grams
2 - 99 grams
They seem all to be pretty close and the scale does move + or - 1 gram.