种类 (zhǒng lèi) is a general noun meaning 'kind, type, category' — it refers to a class or sort of things. 类 (lèi) is similar but often used as a suffix or in compounds (e.g., 人类 'human race'), while 类型 (lèi xíng) emphasizes a specific 'type' or 'genre' with shared characteristics. 品种 (pǐn zhǒng) is narrower, meaning 'breed' or 'variety' of plants/animals/products.