两个都有而不是的意思.
instead of也有代替的意思.是个介词词组,后面通常跟名词、代词或动词的-ing形式等.
Instead of giving him the money,she gave it to me .
I want to be a tour guide rather than an English teacher.
I will play basketball instead of swimming.
rather than 它的意思是而不是.常用于平行结构,用来连接两个词性相同的,并列的成分.
rather than后跟动名词时是个介词短语,表示“而不是,”相当于instead of .
(http://zhidao.baidu.com/question/28149118.html)
rather than,more...than,other than的用法
rather than,more...than,other than的用法
（1）rather than 用来表示“是.而不是.”,通常连接两个并列成分
eg:He is an artist rather than a philosopher.
他是位艺术家而不是位哲学家.
（2）sb/sth is more A than B表示“与其说sb/sth是B,不如说是A”
eg:He is more an artist than a philosopher.
与其说他是位哲学家,不如说他是位艺术家.
sb/sth is not more A than B表示“与其说sb/sth是A,不如说是B”
eg:He is not more an artist than a philosopher.
与其说他是位艺术家,不如说他是位哲学家.
注意：这里的not more...than 与疑难短语（一）中所讲的不同,疑难短语（一）中所讲的not more...than所作比较的是主语和than后面的词语,而这里所讲的not more...than 所作比较的是than前和than后的词语,要注意区分.
(http://www.***.cn/viewthread.php?tid=14525)
instead of 用法归纳
Some people seem to think that sports and games are unimportant things that people do, at times when they are not working, instead of going to the cinema, listening to the radio, or sleeping.
Instead of 的意思是“代替……”、“而不……”,其主动用法如下：
1． 作为短语介词,instead of 后面常跟名词、代词和动名词,偶尔也跟复合结构.例如：
I have come instead of my brother. He is ill.
I will go instead of you.
If I hadn’t got a cold I’d be working instead of lying here in bed.
Instead of doing it himself, he got a man to do it.
Instead of lending a hand, he laughed at us.他不仅没有帮我们一把,反而嘲笑我们.
They must make up their own minds instead of our making up their minds for them. 他们必须自己做出决定,而不是有我们来代替他们作决定.
It’s me that should ask you instead of you asking me. 应该是我问你而不是你问我.
2． Instead of 后面还可跟形容词、副词、动词、不定式、介词短语和从句,这时他相当于连词,但也有不少人认为他们是介词.但是,对中学生来说,重要的不是他的词性,而是他的用法.请看下面的例句：
Taking exercise every day makes him look younger instead of older. 每天锻炼身体使他显得更年轻而不是苍老.（连接形容词）
But the businessman grew worse instead of better. 但这位商人的情况没有好转,反而进一步恶化了.
I go to bed late instead of early.我总是很晚才睡.（连接副词）
That increased instead of decreased our courage. 这增加而不是减少了我们的勇气.（连接动词）
The price rises every day instead of sinks.
He proposes to do some work instead of to watch television.他提议做些工作而不是看电视.（连接不定式）
A word of encouragement might have made me respect instead of hate him.他若是说一句鼓励的话,那么我或许不会恨他,反而会敬重他.（连接不定式）
In warm weather he often reads under a tree instead of in the library.
天气暖和的时候,他常常是在树下而不是在图书馆里读书.（连接介词短语）
As a result, silver begar to flow out of, instead of into, the country.
结果,银开始流出而不是流入该国.
(http://hi.baidu.com/chenwlcn/blog/item/031659c25256de35e5dd3b1f.html)
3． Instead 单独使用的时候式副词,常用于句末.例如：
We’ve no coffee. Would you like tea instead.
我没有咖啡了,喝茶行吗?
It will take days by car, so let’s fly instead..
坐汽车得好几天时间,所以我们还是改乘飞机吧.
不过,用instead的句子也可以改成instead of：
She never studies. Instead, she plays tennis all day. à Instead of studying , she tennis all days. 她成天打网球,而不是学习.
He didn’t give John the money, but he gave it to me instead. à Instead of giving John the money, he gave it to me.