Actually...
Pixies may be small, but they're not tiny little lights. According to lore, the "faerie lights" or the "faery fire" that most people associate with fae, i.e. little bright sparky thingies that zip and float around like fireflies, are actually a mark of the glamour the Folk are using to beguile and beglamour mortals.
Pixies are most commonly associated with these lights because the lore says they're best at it. Technically, however, the pixies are actually just a derogatory slang word for the Picts, like Gypsies for the Rom.
That being said, DR490NW4RRI0R is quite right. Faeries were originally human sized, or at least, not teeny bug sized. Truth be told, the fae range in size on an even broader scope than humans do. And, if we're specific, some fae really are very small, three to six inches in height. They're not Sidhe, of course, but they are still fae.
Those aren't pixies, though. Pixies are actually about two to three feet in height, if we're to listen to the lore.
In any case, fae can be whatever size they want to be: they're shapechangers and trickster-folk, save for a few kinds in the Courts.
*chuckles* Gods, I can't believe I'm sitting here clarifying about the fae... Too much woogy in my life, I need a break. Or a drink. Or both.
