区别 (qūbié) is a versatile word that works as both a noun ('difference') and a verb ('to distinguish'). As a verb, it's very close to 区分 (qūfēn, HSK6), but 区别 is more common in everyday speech for telling things apart, while 区分 often implies a more careful or systematic classification. As a noun, it's interchangeable with 差别 (chābié, HSK5) for 'difference', though 差别 can carry a stronger sense of disparity or gap.