'Ocha' is a general word for tea, usually referring to green tea, while 'maccha' is the powdered form used during the sadou. They are written お茶 and 抹茶 respectively.
Japanese in sense of the language: 日本語 /ni hon go/. Japanese in sense of person(s) from Japan: 日本人 /ni hon jin/.Japanese in sense of the nationality: 日本国籍 /ni hon ko ku se ki/.