Leprechauns: Are they gnomes?

Just in time for St. Patrick's Day, a mystery: are leprechauns gnomes? They are typically classed as a type of fairy, but they run perilously close to being gnomes -- goofy hats, often unaccountably and pointlessly jolly, impish senses of humor, trickster natures, a keen sense of mischief, and a desire to pull a fast one on humanity.

Some of the classic representations of them make me think maybe they are, in fact, gnomes. I mean, if you didn't know this was a leprechaun, you surely might mistake him for a gnome, no?

The "Leprechaun" movies certainly tried to warn people of the dire threat leprechauns posed humanity.

I don't know whether they are gnomes, or are merely Celtic cousins of gnomes, or are entirely unrelated. Certainly if you put Tinkerbell, a gnome, and a leprechaun in a lineup, most Gentle Readers would be hard-pressed to lump the leprechaun on the pixie side of the equation, toward Tinkerbell -- rather, the leprechaun would caucus with the gnome.