①call for把 ……  来 （有需要的口气)

Call for a taxi if you need it.需要的话你可以叫个的士来

Someone is calling for help.有人在大声呼救。

②call out唤起；出动；大声叫唤

From inside the room, they heard the nurse call out for her.这时他们听到房内传来奶妈叫唤茱丽叶的声音

He called out to the children and threw the ball back to the bank.他大声招呼着那些小孩,并把球抛回到岸上。

其它用法：

call in:

(1) 叫…进来；叫…进去

ask to come or go in

例句：

Please call Comrade Shen in.请叫沈同志进来。

I waited for only two minutes before I was called in.我只等了两分钟就被叫进去了。

(2) 邀请召来；召去

例句：

He called all the workers in for a conference.他召集全体工人开会。

How many friends did you call in?

你邀请了多少朋友？

Let's call in a doctor for the baby.

让我们请上医生来瞧瞧这孩子吧

区别就是两者都是动词call的短语，但意思是不一样的，具体的不同如下

call out 中文意思是召唤；向某人大叫

I'm about to call out to them. They run away.我想要呼唤他们，他们却恰好跑开了。

call for 的中文意思是v. 要求；需要；提倡；邀请；为……叫喊；前往接某人

It will be put up for sale under the terms already communicated to you, which, to recapitulate, call for a very minimum of publicity.其销售将按照已讲的条件进行，概括地说，就是要求尽量少宣传。