本人刚考了英语四级650分，正好复习过这两者的区别，下面就试着来回答一下，请先参考表格：
【词组含义】
be in 有到达和执政的意思,一般表达为在某地,用现在完成时来表述。
be on 表示一个动作已经开始了,现在正处于这个动作上。
【用法】
一、be in的用法
1、My wife won't be in until five o'clock.
我妻子要到五点钟才在家。
2、Will she be in tonight?-I think so.
她今晚在家吗？-我想在家。
3、The new model will be in production by the end of the year.
新型号将于年底投产。
4、I'd like to be in on the plan.
我很想参与这项计划。
5、By this time next week we'll be in New York.
下星期的这个时候我们将在纽约。
6、Students are required to be in school by 8.30.
学生须在8:30以前到校。
7、She would be in bed by now, as like as not.
这工夫她很可能睡了。
8、All we need is a car and we'll be in business.
我们所需要的只是一辆车，然后我们就准备就绪了。
9、This action would not be in accord with our policy.
这一行动不会符合我们的方针。
10、The increase will not be in excess of two per cent.
增加幅度不会超过百分之二。
11、The house was reported to be in excellent condition.
报告说明这房子的状况极佳。
12、I'll be in town next week if you want to meet.
如果你想见面的话，我下个星期在城里。
13、Applications should be in by next Monday at the latest.
最迟须于下星期一递交申请书。
14、Why would the closure of hospitals be in the public interest?
关闭医院怎么会对民众有利呢？
15、He pronounced the country to be in a state of war.
他宣布全国进入战争状态。
16、Annual pay increases will be in line with inflation.
每年加薪幅度将与通货膨胀挂钩。
17、This time tomorrow I'll be in Canada.
明天这个时候我就在加拿大了。
18、If I don't get this finished in time, I'll be in trouble.
我如不按时把这完成就要倒霉了。
二、be on的用法
1、Chinese will be on the school schedule from next year.
从明年开始中文将排进学校的课程表。
2、I like to be on my own sometimes.
有时候我喜欢一个人待着。
3、I'll be on call the night of the party.
在聚会的晚上我将随时听凭召唤。
4、The latest models will be on display at the motor show.
最新的车型将会在这次汽车展上展出。
5、Your car isn't fit to be on the road!
你的车子还不适合上马路！
6、The cast must all be on set by 7 in the morning.
全体演员必须在早上7点钟到场。
7、The latest computers will be on show at the exhibition.
最新型的计算机将在展览会上展出。
8、No offence, but I'd really like to be on my own.
我无意冒犯，但我确实想自己一个人。
9、The latest software will be on parade at the exhibition.
最新电脑软件将在展览会上展出。
10、The public should be on the lookout for symptoms of the disease.
公众应当留心这种疾病的症状。
I'm not at in. 我不在家。
be on=be happening 在进行，在发生
A film is on at the cinema now. 电影院正在播放一部电影。
该短语是be out的反义表达，表示“在家里”。如：
I went to Ted's house and asked to see him, but he wasn't in.
be on
该短语表示“在上映；在广播”，一般用于电影电视或广播的进行中。如：
What's on at the local cinema this week?本回答被网友采纳