それとも vs または vs あるいは vs もしくは

Or; or else, when offering an alternative

それとも means or and is used to present two alternatives and ask which one holds or which to choose. It is a conjunction placed before the second alternative, and both sides should be parallel in structure and usually end as a question with か or rising intonation, as in バスですか、それとも車ですか. Keep the predicates balanced on both sides and use question form throughout, since mismatched endings or a final period make the choice unclear.

1. あれはバスですか、それとも車くるまですか。

   Is that a bus or a car?

2. そこへバスでいきますか。それとも車でいきますか。

   Do you go there by bus or by car?

Used to link choices: one option or the other; either of two alternatives

または presents two alternatives and means or, with the sense that one of the options holds. It is placed between two nouns or noun phrases, as in A または B. It is formal and common in writing, announcements, and polite offers, where casual speech would often use か or それとも.

1. 紅茶こうちゃまたはコーヒーはいかが？

   Would you like some tea or coffee?

2. ユーザー名またはパスワードが間違っています。

   Either your user name or password is incorrect.

or; either...or; as another option; maybe

あるいは connects two alternatives in the pattern A, あるいは B, meaning or or either A or B. It can join nouns, phrases, or whole clauses, and it can also appear at the start of a sentence to offer another possibility. When paired with expressions of uncertainty like かもしれない, it adds the sense of perhaps or maybe. It sounds formal and is common in writing, announcements, and polite explanations.

1. あるいはそれは本当ほんとうかもしれない。

   Perhaps that's true.

2. これらは一家族あるいは一族を表すものである。

   These figures are signs of a family or clan.

or; either ... or

もしくは means or and presents two or more different options as alternatives to choose from or to cover. It is a formal conjunction common in written notices, application forms, and business language rather than casual conversation. It is placed directly between nouns, verbs, adjectives, and full clauses in their plain forms, as in 欠席もしくは遅刻 and 来るもしくは来ない. It is not used to rephrase the same idea in other words or to show an approximate number range.

1. 彼かれは英語えいご、フランス語ご、もしくはドイツ語ごを話はなせますか？

   Does he speak English, French or German?

2. 過去３週間で、オーストラリアもしくはニュージーランドに行ったことがありますか？

   Have you been to Australia or New Zealand in the past three weeks?