Tea in Japanese is お茶(ちゃ)(ocha) and if you ask for お茶 in Japan, you will probably get a cup of hot “green tea.” However, you may come across a package like the one in the photo and/or a menu item called グリーンティー written in Katakana in Japanese style cafés. Usually these グリーンティー and お茶 are quite different.
お茶 green tea is usually prepared by pouring hot water over dry green tea leaves. It is usually made in a pot called 急須(きゅうす)and people drink it from a handle-less cup called 湯呑(ゆのみ). Japanese people never put any sugar or milk in their お茶. However, グリーンティー in Katakana is usually a mixture of 抹茶(まっちゃ)powder and sugar and mixed with water or milk to serve as a cold drink.
抹茶(まっちゃ) is the green tea powder used in tea ceremonies. Although some packaged tea leaves can contain a small amount of 抹茶(まっちゃ) to enhance the flavour, 抹茶(まっちゃ)is usually not part of everyday drinking tea.
Depending on the ingredients and preparation methods, お茶 green tea is divided into several different kinds such as 煎茶(せんちゃ), 玉露(ぎょくろ), ほうじ茶(ちゃ), 番茶(ばんちゃ), 玄米茶(げんまいちゃ), etc. If you compare them, they taste quite different. Some tea speciality shops will let you do “tasting.” If you like green tea, try it when you go to Japan!