Vearth

Vearth (大地 (ヴァース), Vāsu, kanji means "Great Earth"; Varse in the Viz Manga and in FUNimation edited dub) is the name given to dirt by the people of Skypiea. Because Upper Yard is the only place in Skypiea where Vearth can be found, it is considered a sacred substance.

Before the events of Skypiea arc, the Shandian Aisa would usually sneak into Upper Yard and fill up her bag with Vearth, bringing it back home with her.

During the events of the Skypiea arc, Upper Yard was off limits to civilians. Anyone who entered was killed by Enel.

The dirt on Upper Yard and Upper Yard itself originates from the island Jaya directly below Skypiea. Originally, Upper Yard was mearly a piece of the island, but after a Knock Up Stream appeared beneath Jaya, it was shot up to Skypiea never to be seen again by the denizens of the blue sea.

Fairy Vearth
Fairy Vearth (限りない大地, (フェアリーヴァース), Fearī Vāsu, kanji means "Endless Great Earth"; Endless Vearth in the FUNimation dub and Endless Varse in the Viz Manga) is a legendary land that Enel mentions throughout the Skypiea arc. Enel wanted to travel to Fairy Vearth after he destroys Skypiea. For this purpose he built his ship, Maxim.

After being defeated by Luffy, Enel headed off to Fairy Vearth, which turns out to be the Moon. There he found a group of alien like creatures who have wings similar to the Skypieans, which Enel befriended.

The discrepancy in translation ("Endless" Vs "Fairy") is because both are actually written in the manga. The Kanji written lists it as "Endless Great Earth" while the Furigana reading is for "Fairy Vearth", meaning technically, both are correct.