Some of the "Fairy Tail" manga and anime arcs include the Oración Seis arc, the Phantom Lord arc, the Edolas arc and the Tenrou Island arc. There are currently 17 total arcs in the manga and 15 in the anime. The anime is two arcs behind the manga.
Several of the arcs in the "Fairy Tail" anime are quite a bit shorter than the same arc in the manga. Examples of this include the beginning arc of the story, usually called the Macao arc, and the next two arcs called the Daybreak and Lullaby arc, respectively. Generally the anime arcs are about half as long as the manga arcs in terms of episodes to chapters.
The longest arcs in the "Fairy Tail" are the Grand Magic Games arc, the Key of the Starry Sky arc and the Tenrou Island arc. The manga is currently in the Tartarus arc, which began in volume 42 and has not yet ended. The anime is in the Grand Magic Games arc and has already run 43 episodes to bring the anime's total aired episode count to 193. At least an additional three episodes are planned and titled but have not aired as of August 2014.