Fairies have many of the same characteristics as spirits, but they are a distinct species.
They have natural objects that they are responsible for, but the natural objects they are responsible for are much more specific than the natural objects that elementals are responsible for.
They are also characterized by the fact that they control the natural objects they are responsible for and use them in a skill-based manner, rather than treating them as their own.
As a species, they all have pointed ears. They also tend to live in groups of fairies who are responsible for similar natural objects.