noun
different matter; separate issue; another question
Used to assert that something is unrelated to the current topic, or should be treated as a distinct case. Often appears in phrases like それは別問題だ (that's a different matter).
能力があるかどうかと、やる気があるかどうかは別問題だ。
Whether you have the ability and whether you have the motivation are separate issues.
彼の
His opinion is interesting, but whether it's correct is another question.