Choosing between 大丈夫 or いい when asking/giving permission


It seems like 大丈夫 and いい can be used interchangeably when asking or giving
permission.

For example when asking for permission, you might use:

  * 「...てもいいですか」 vs 「...ても大丈夫ですか」
  * 「...はいいですか」 vs 「...は大丈夫ですか」

Similarly, when answering such a request (with a positive response), one might
say:

  * 「いいです」 vs 「大丈夫です」

Is my understanding correct that they are indeed interchangeable? If they are,
can I reply to the request with the "other" word (e.g., 「...てもいいですか」 ->
「大丈夫です」; or 「...は大丈夫ですか」 -> 「いいです」)?

If they aren't interchangeable, when should I use one or the other?




「...てもいいですか?」 and 「...ても大丈夫ですか?」 are as you said. For example, when you are
asked "これ飲んでもいいですか?" or "これ飲んでも大丈夫ですか?", you can say both "いいです" and "大丈夫です".
However I think you don't need to change the word.

「...はいいですか?」 and 「...は大丈夫ですか?」 generally mean "Is ～ OK?", "Is ～ all right?"
and "Is ～ good?", not asking for permission. In this case, I think you
shouldn't use the "other" word. For example, when you are asked "体の具合はいいですか?",
you should say "いいです". When you are asked "体の具合は大丈夫ですか?", you should say
"大丈夫です". When you are asked like "体の具合はどうですか?", you can say both "いいです" and
"大丈夫です".




「...てもいいですか?」 and 「...ても大丈夫ですか?」 are as you said. For example, when you are
asked "これ飲んでもいいですか?" or "これ飲んでも大丈夫ですか?", you can say both "いいです" and "大丈夫です".
However I think you don't need to change the word.

「...はいいですか?」 and 「...は大丈夫ですか?」 generally mean "Is ～ OK?", "Is ～ all right?"
and "Is ～ good?", not asking for permission. In this case, I think you
shouldn't use the "other" word. For example, when you are asked "体の具合はいいですか?",
you should say "いいです". When you are asked "体の具合は大丈夫ですか?", you should say
"大丈夫です". When you are asked like "体の具合はどうですか?", you can say both "いいです" and
"大丈夫です".

