Japanese:
* Vertical writing: Japanese is primarily written vertically, from right to left and top to bottom.
* Two writing systems: Kanji (Chinese characters), Hiragana (phonetic script for Japanese sounds), and Katakana (phonetic script for foreign words and sounds) are used together.
* Mix of characters: You'll see a mix of large complex Kanji characters alongside smaller, simpler Hiragana and Katakana characters.
* Rubi: Often, small Hiragana characters are placed above or beside Kanji characters to indicate pronunciation.
Chinese:
* Horizontal writing: Chinese is primarily written horizontally, from left to right.
* One writing system: Characters are all simplified or traditional Chinese characters, without separate phonetic scripts.
* Mostly complex characters: Chinese characters tend to be more complex and intricate than Hiragana or Katakana.
* No Rubi: You won't see smaller characters alongside larger ones like in Japanese.
Exceptions:
* Horizontal Japanese: Japanese can sometimes be written horizontally, especially in modern publications.
* Simplified Chinese: Simplified Chinese characters are simpler than traditional Chinese characters, and some may resemble Japanese Kanji characters.
In Conclusion:
While it's not foolproof, looking at the writing direction, complexity of characters, and presence of phonetic scripts can give you a good indication.
If you're unsure, try looking for online resources that specialize in identifying languages based on their writing systems.