1、say 是及物动词，表示讲某事，说某事，强调的是说话的内容；speak 作为不及物动词时，强调说话的这个动作而已。作及物动词时，后面只能跟某种语言。
2、say 较口语化；speak 比较正式，是书面用语。
3、speak 没有被动语态，say 有被动语态。
例句：
1、He disagreed, but he didn't say anything definitive.
他尽管不同意，但是没有把话说绝。
2、He was just going to speak when he thought better of it and didn't mention it for the moment.
他刚想开口说话， 但一转念， 觉得还是暂时不提为好。
3、She can speak German and French, not to speak of English.
她能说德语和法语，更不用说英语了。
4、These words were said in 1961, by FCC chairman Newton Minnow.
这些话是FCC（联邦通信委员会）主席纽顿·米诺在1961年发表的看法。
扩展资料
相关短语：
say when [俚语]停止；制止
say for oneself 为自己找借口，为自己辩护
say yes vt. 同意（允诺，承认）；说对
say about 说到
how to say 怎么说
nothing to say 无话可说
say on v. 说下去
generally speaking adv. 一般而言
speak english 说英语；讲英语
speak for oneself 发表个人意见；说自己的事；为自己辩护
so to speak 可以说；打个譬喻说
speak of 谈到；论及
frankly speaking 坦白地说
speak with 和…商量；和…谈话
speak out 畅所欲言；大胆地说；大声地说
speak in 用某种语言说
speak up 更大声地说；无保留地说出