正式用词，一般指大型会议，如政府工作会议、国际学术交流会议、各国之间的协商、会谈等；(专门性的)会议，讨论会

例句：

The conference on international economic problems met in Geneva

关于世界经济问题的会议在日内瓦召开。

They were pointedly absent from the news conference.

他们有意缺席了那场新闻发布会。

A conference on women's rights

妇女权利大会

I'm speaking at/attending a conference next week.

我下周要在一个会议上发言／出席一个会议。

Should I book the conference room for the meeting?

我应该为会谈预订会议室吗？

指国会、议会、代表大会等机构，尤指经选举产生的国家立法机构的大会或由这些机构召开的大会，也可指专业人员代表大会。

例句：

an international/medical congress

国际／医学代表大会

the congress of the Australian Council of Trade Unions

澳大利亚工会委员会代表大会

Both houses of Congress have rejected the recent presidential proposal on gun control.

国会两院否决了总统最近关于枪支的提案。

Congress passes laws that must be obeyed by the people.

美国国会通过的法律，人民一定要遵守。

指多人的、有计划的集会。

例句：

He was to address a public assembly on the issue.

他要对公众集会发表演说谈论这个问题。

the United Nations General Assembly

联合国大会

She has been tipped as a future member of the Welsh Assembly.

大家预测她将会成为威尔士议会议员。

The assembly of students takes place in the auditorium.

学生们在大礼堂举行集会。