Tsipouro, tsikoudia, and raki are all the same spirit and, unlike ouzo, they are grape distillates. The alcoholic grade of tsipouro is higher than ouzo and can, therefore, be considered stronger, but ouzo is said to give worse hangovers! Tsipouro is believed to have originated in the 14th century in Mount Athos before spreading to the rest of Greece.
Tsipouro can also have anise in it making it sweeter - more commonly found in the north of Greece, especially in the regions of Thessaly and Epirus. This spirit is usually drunk straight and not diluted in water or ice, but always accompanied by lots of mezedes! If you come to Greece, be sure to visit an authentic tsipouradiko (meaning; the small restaurants serving tsipouro and meze dishes). The best are found in Volos, where you can order a 200ml bottle of tsipouro and get a free plate of mouth watering mezedes.