～かは～によって違う【かは～によってちがう】

～かは～によって違う says that the answer to a question changes from one case to the next: "what/how/whether … depends on …". The question goes first as a clause ending in か, は makes it the topic, and によってちがう違う names what it varies with.

The question clause is in the plain form: polite です and ます don't go inside it.

Question word or かどうか

With a question word – なん何, どこ, いつ, いくら, どのくらい – the clause ends in plain か. Without one, it is a yes/no question and ends in かどうか, which a noun or a な-adjective takes without だ: ×学生だかどうか.

によって違う or 次第だ

によって違う says the outcome is different for each value of the factor – each shop, each person, each season. しだい次第だ says the factor decides the outcome, and fits a single result that hangs on effort or a choice.

• × 合格できるかどうかは努力によって違う → 合格できるかどうかは努力次第だ

Usage notes

These go beyond the spoken form with 違う.

異なる and 変わる

ことなる異なる replaces 違う in writing. かわる変わる says the answer changes rather than differs.

による

による ends the sentence with the same meaning and no 違う: ねだん値段がいくらかはみせ店による, "it depends on the shop".