For example, words for things like "pixie," "goblin" and "elf" are fairy gendered, whereas the words for "ogre," "dwarf," "chicken" and "cow" are human gendered.
Gender isn't just used literally though, but also more loosely, to things and concepts that have characteristics associated with one realm or another, bearing in mind that this is a language OF fairies, not just a language ABOUT fairies, and their perceptions will color the choice of gender.
Fairies see themselves as peaceful, pure, wise, sophisticated and appreciative of beauty, and humans as brash, impulsive, culturally primitive (but technologically superior) and driven by their baser needs. In reality, many humans are wise and sophisticated, and many fairies are impulsive and vulgar (especially if you include gremlins and goblins in the fairy category, which for the purposes of this conlang, I do), but this is about perception.
The angelic gender is used mainly for religious and spiritual concepts, whereas the demonic gender is used for anything wretched, loathesome or evil.
The actual differences between the genders is mainly in the form of a vowel change, but the are also differences in some consonants.