用词典查询“代表”，有delegate, duputy, represent, behalf几种解释，都属于高频词汇。
百度了一下，大概是这样的区别：
delegate通常特质某一会议的代表
representative一般是被选举或委派代表某个人或者团体的人，职务有时候是长期的
duputy是上级委派行驶自己职权的人
我的感觉是：
只有duputy的意思比较明确，通常就是类似副手的意思。
delegate和representative貌似并没有明显的区别
behalf都是跟着on behalf of这个短语一起走的，意思跟前两个也差不多，只是语法的差别。
另外delegate可以做动词用，representative可以变形为represent做动词用，behalf则只能做状语（~_-!!状语是什么）。
delegate
vt. 委派…为代表
n. 代表
指一般被派参加某一会议的代表。
He is one of the delegates to the conference.(他是与会代表之一。)
They have delegated him to represent their city at the convention.
他们选举他代表他们市去参加代表大会。
They drafted him to serve as their delegate。
他们选派他作他们的代表。
Should I delegate this task or just say no all together?
我应该把这个任务委托给别人，还是直接拒绝？
He delegated his voting right to his secretary.
他把他的选举权委托给了他的秘书。
deputy
n. 代理人，代表
adj. 副的；代理的
I delegated my responsibilities to my deputy.
我把职责委托给了我的代理人。
The Premier deputed the Foreign Minister to act as his deputy.
总理委派外交部长作为他的代表。
"We may not like them, " he is reported to have told James Steinberg, deputy US secretary of state, but "they are a neighbour"
“我们可能不喜欢他们，”据说他对美国副国务卿史坦博格这样说道，但是“他们毕竟是我们的邻居。”
representative
adj. 典型的，有代表性的；代议制的
n. 代表；典型；众议员
We all voted for him as our representative.大家都推举他当代表。
You should come or send a representative at least.
你应该来，或者说，至少派一位代表来。
The premier accredited Mr. Bush as his representative.
总理委托布什先生作为他的代表。
represent
vt. 代表；表现；描绘；回忆；再赠送
vi. 代表；提出异议
这是representative的动词形态，不过值得注意的是，他同时还有描绘、陈述等含义。
1.代表
This mark represents a village.
这个符号表示村庄。
His opinion represents that of the majority.
他的意见代表大多数人的意见。
2.描写；描绘；表现：
She represented her little brother as a simpleton.
她把她的弟弟描绘成一个傻瓜。
This painting represents the end of the world.
这张画描绘的是世界的末日。
3.陈述；阐述；指出；主张：
Let me represent my ideas to you in another way.
让我用另一种方式向你说明我的想法。
on behalf of
behalf貌似就on behalf of这一种用法
代表…一方；代表(或为)…说话，作为…的代表(或代言人)
为了；为了…的利益
He spoke on behalf of all the members of the faculty and staff.
他代表全体教职员工讲了话。
On behalf of my Government I have the honour to make to you the following communications.
我荣幸地代表我国政府向您转达如下内容。
There is one database heap per database, and the database manager uses it on behalf of all applications connected to the database.
每个数据库都有一个数据库堆，数据库管理器使用它来代表连接到数据库上的所有应用程序。