What's the difference between 度 and 回?


Both are counters for occurrences. Would they be interchangeable in the
following sentence?

パリ行きの電車は一日に二回出発します。




The followings with the sign "OK" are correct and used by Japanese nateives,

  * OK: "何度もチャレンジする"
  * OK: "何回もチャレンジする"
  * OK: "３度目でやっと成功した"
  * OK: "３回目でやっと成功した"
  * OK: "試しに一度やってみたら？"
  * OK: "試しに一回やってみたら？"
  * OK: "早稲田には１回で合格したが、司法試験は３回（目）でやっと合格した。"
  * OK: "早稲田には１度で合格したが、司法試験は３度（目）でやっと合格した。"
  * OK: "第67回NHK紅白歌合戦"
  * NG: "第67度NHK紅白歌合戦"

"今回はリハーサルです。" = "This time it is the rehearsal." "今回" means "this time"

"次回はリハーサルです。" = "Next time it'll be the rehearsal." "次回" = "next time"

"今度はリハーサルです。" = "Next time it'll be the rehearsal." "今度" = "next time"

We never use "次度" at all.

Some people say that "回" has clear time window, but "度" donesn't have it.

I'm for it, but I feel that it is not the well-grounded explanation.

For me, the following is the best explanation for the difference between "度"
and "回."

"一度で済ませた。" = "I've got done with them at one time."

= "I've got done with variou tasks at one time."

"一回で済ませた。" = "I've got done with them at one time."

= "I've got done with the task not at several times but at one time."

= "I've got done with the task on the first time."

