帮我介绍一下on time和in time的用法

in time 及时,不迟
例句 Will I be in time to catch the train.
我赶得上火车吗?
on time 按时,准时
例句 The train arrived on time.
火车正点到达.

on time 按时
in time 及时
比如九点钟上课，刚好九点就是on time，在九点以前就是in time

on time 是按时，in time 是及时。