Kanji vs. Vocabulary

[jneapan]

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Onyomi v kunyomi readings

Kanji are individual separate isolated characters, and vocabulary are actual words that use the kanji, actual real words. The pink quiz is for the character. Those can have multiple readings depending on the vocab they appear in. You learn a “main” reading for it, but it won’t mark you wrong if you answer another, it will just not accept it. The purple quiz is for the words. Words typically (99% of the time) only use one valid reading. Words are more strict. It’s the actual words that Japanese…

The FAQ also covers this a bit:

What are radicals, kanji, and vocabulary?