"They are different."
I do not think so, 「彼らは変わっています」 means either "They are strange" or "They are changing", but not "They are different".
I see. However we often say " <they are> different " to mean " they are strange" and also to mean " they are distinct from others" depending on context.
Thank you for your suggestion. I immediately looked it up in a dictionary and found "strange" was one of translations of "different", but with a comment "it is colloquial (e.g. http://ejje.weblio.jp/content/different). This may be a reason why 「変わっている」 is not included in the correct answers (to avoid learners' confusion).
Anyway, I learned a lot through this communication and would like to thank you.
Not at all, I'm happy to help, and I understand the need to limit scope sometimes. A similar phrase is " <he is> funny " with the meaning of 'strange / 変わっている'
I learnt something too :-)
「彼らはそれぞれ違う」 means "They are diverse", "The members of them are different each other", while 「彼らは異なる」 means "They are different from other people (or things)".
So to translate "それぞれ違う" we might say "they are all different" or they are 'diverse'