In time vs. On time

The difference between "in time" and "on time" sometimes is blurred.
In time indicates that you have arrived for a particular event early or soon enough to do something.Before the last moment.In time usually comes with" just".

- He arrived just in time for dinner.
- If I didn't hurry up, I wouldn't be in time to get to work.
- If I hadn't arrived in time , she would have killed herself.

On time indicates that you arrived somewhere at the appointed time and not late or not early.It sometimes comes with" right".

- In japan, trains are always on time.
- I may be up watching T.V until midnight ,but I am always on time for my work.
- The conference ended just right on time.

To understand better the difference between the two, notice the following sentences:

- The exam will begin on time. If you want to be calm and without stress you should attend the school in time .
- Trains in this country depart the station on time.If you want to catch the train ,you must arrive in time.