かOr

Both か and それとも present alternatives. か directly follows nouns to mean 'or' (e.g., 今日か明日休みます = 'I'll take off today or tomorrow'). In contrast, それとも means 'or' as well, but is used at the start of sentences or questions, not directly after nouns (e.g., 今日休む？それとも明日にする？ = 'Will you take off today? Or [will you do it] tomorrow?').

Both か and あるいは present alternatives. か is casual and follows nouns to mean 'or' (e.g., 今日か明日休みます = 'I'll take off today or tomorrow'). あるいは is more formal, mainly used in writing or formal speech (e.g., 新品で買うか、あるいは中古で買うか、まだ決めていません = 'I haven't decided yet whether I'll buy it new or perhaps second-hand').

The particle か can follow nouns to mean 'or,' clearly specifying alternatives (e.g., 今日か明日休みます = 'I'll take off today or tomorrow'). On the other hand, でも, which also follows nouns, means 'or something,' suggesting an open-ended alternative (e.g., お茶でも飲みましょうか = 'Shall we drink tea or something?').

Both uses of か are extensions of its basic function as a question particle. When following a Wh-question word (like who, what, where, why, how), it creates a phrase meaning 'some-(word)' (e.g., 誰か = 'someone,' どこか = 'somewhere,' いつか = 'sometime'). When following regular nouns, it means 'or' (e.g., 今日か明日休みます = 'I'll take off today or tomorrow').

～なり～なり is a somewhat formal or literary expression used to provide examples, typically implying additional options or suggesting that the speaker doesn't mind which option is chosen. In contrast, the question particle か is used after nouns to present alternatives or offer a choice between two or more items (e.g., 今日か明日休みます = 'I'll take off today or tomorrow').