Why both kanji and katakana or hiragana?
The simple answer is yes, katakana is different from kanji. The longer answer is written Japanese uses kanji, katakana, hiragana, and romaji, as follows:
- Kanji; these are the characters derived from Chinese characters that Japanese use for verb stems, adjectives, nouns, etc.
- Hiragana; these are syllabaries (46 characters, each representing a phonic) used for verb endings (such as past, present, and future tenses), conjugation, etc.
- Katakana; these are also syllabaries (actually 46 simplified forms of the corresponding hiragana character) used to write foreign nouns, both for objects and people names.
- Romaji; these are the alphabet characters, generally restricted to advertising use and acronyms.