On time, in time

今日この質問はYさんに聞かれた：

質問があるんだけど、on time とin time はどう違うの？ I will be on time とI will be in time は、「時間ちょうどにいるよ」と、 「時間以内にいるよ」、でいいのか な？

Yes! Ms. Y is mostly correct in her own answer!

▲On time

Means you are personally involved, for a meeting, class, or if you want to stress the point of something not being late.

例えば、

◇The bus was on time.(it was not late)

◇I was on time for the movie(i was not late)

◇She is always on time for our dates! (She is never late)

▲In time

Means that because you are not late, you can have a chance.

例えば、

◇I made it in time for the movie. (So i could have the chance to watch it)

◇i prepared the presentation in time for the meeting (so i could use it)

◇The police arrived in time to catch the thief. (They could have a chance to catch him)

★sometimes you can add "just".

ギリギ リの感じてす。Or it could mean "at exactly the right moment, not late"

-I made it just in time to catch the train!

-i arrived just in time to catch my girlfriend kissing another man!ι(｀ロ´)ノ

In many instances, it may be ok to use "in time" or "on time", but the nuance is a little different.