Elves: I like stretching the definition of things and coming up with unusual variants on mythological creatures. It is for this reason that the elves of Essu Beti are marsupials, have rat-like, prehensile tails, and are also crepuscular obligate carnivores that require about, oh, 70% of their diet be based on meat. They don't handle carbohydrates well, and a number of things that humans can eat, such as chocolate and onions, will kill them dead in a high enough dose. And no, of course there haven't been any substantial effects from releasing what is essentially an apex predator into an environment that hasn't yet learned to fear them. Why ever would you think that? /sarcasm
Elves are, in general, slightly smaller than humans- they average 100-120 lbs apiece, with the elves of Essu Beti generally averaging closer to 90 because of nutritional issues- this is likely to change once the food situation stabilizes and children are born into the country instead of coming from a place with systemic oppression and resultant inability to obtain good food. Elven women, called "jills" in some nations such as Creatan (Essu Beti calls them "elven women"), tend to be about 20% smaller than elven men, or "jacks" (again, only called that in some places). Elves are also marsupials, and while I can't go into much detail about that on this website, suffice to say that there are no appreciable differences in build or body shape between jills and jacks and that most humans end up guessing based on general size.
Cone-shaped, highly mobile ears that are basically what lets me call them elves instead of a homebrew not-furry species.
Tails that reach down to the floor, have scutes like rat tails, and are also highly mobile and are often used like an extra limb. They are accommodated for in Betian clothes, chairs, cars, and vehicles, especially the latter- getting your tail caught in bike spokes hurts a lot.
Hands and feet have claws instead of fingernails, except for the thumb and prehensile big toe, which do have fingernails. This helps them climb- they're naturally arboreal.
Eyes with a tapetum lucidum that lets them see very well in the dark. Unfortunately, every single one of them is also red-green colorblind. When Essu Beti develops to the point of needing traffic lights, they’ll use shapes to indicate stop vs go lights, in addition to the classic red-yellow-green setup.
Hair with a maximum length of just a few inches. It's also possible for their hair to have color patterns commonly known as agouti (individual strands banded alternating colors), roan (randomized whitening of individual strands of hair), or brindle (red and black striping- google brindle dogs for references. This is exceptionally rare and completely unheard of on Essu Beti, however).
Food sensitivities. Technically not a feature, but there are a lot of things they can't eat and they need to be listed somewhere. Among these things are chocolate, onions, garlic, avocado, grapes, xylitol (it's an artificial sweetener, and PSA IT WILL IRL KILL DOGS DEAD. DO NOT LEAVE XYLITOL FLAVORED GUM IN YOUR PURSE IF YOU HAVE A DOG.) They're also sensitive to alcohol and caffeine, but try to take a Betian's coffee away and they'll take your arm off, whether they're human or elven. It takes a lot less for them to feel an effect, so the elven population either dilutes theirs or makes a single cup last the entire day.
The elves of Essu Beti are mostly of the Kenu ethnic group, with a minority of mostly Tal plus a few Sorkid who had the misfortune of migrating to South Tenahuari just in time for the purges and who opted to remain in Essu Beti instead of going back to their home country.
Humans: You know what humans are. There only real differences in the case of Essu Beti are in vocabulary- human men are often called "johns" and women "janes"- and that Betian humans are, like Betian elves, smaller than the world average because of nutritional deficiencies.
The humans of Essu Beti are pretty much exclusively of homebrew ethnic groups from the original homebrew planet that Betians are from (excluding any weird portal shenanigans to allow for roleplay). If you want to be VERY LAZY AND A BIT INACCURATE, you can say that the Ikkar group is rough equivalent of Middle Eastern in appearance only (this is a homebrew setting so no cultural baggage can be included), while the Sorkid group is the rough equivalent of African along the same terms, albeit in a way which includes the fact that some historical persona along the way lumped together all these varied people into one group for census purposes because they were lazy and racist.
If you want to be EVEN MORE LAZY, you can equivalate elven Kenu with human Ikkar and elven Sorkid with human Sorkid, with the exception that Kenu tend to get the interesting hair color patterns. Tal are not visually distinct because to be honest they're technically a cultural group that tends to integrate and intermarry with whover they end up settling near.