Resolved questions
“觉得”和“认为”有什么不一样？

觉得 juede is
to feel something psychologically or physiologically, it is a more casual term.

觉得疲倦
to feel tiredness

觉得累
to feel tired

觉得兴奋
to feel excited

觉得可以
to feel suitable

觉得有意思
to feel funny

觉得方便
to feel convenient

觉得:表示的语气是不能够肯定也不能够否定，例如，“我总是觉得他说的话有问题,但是呢，又不知道问题出在哪，"表示比不同意他的观点但是又不能否认他的观点。
认为：表示的语气是肯定的，不含有否定的意思。例如“我认为他说的话有问题，所以我投他 一票”

觉得 语气不肯定 ｆｅｅｌ　ｌｉｋｅ　　Ｉ　ｔｈｉｎｋ．．．ｐｒｏｂａｂｌｅｌｙ
认为　语气肯定　ｉｔ　ｓｏｕｎｄｓ　ｍｏｒｅ　ｄｅｆｉｎｉｔｅｌｙ

ｓｕｃｈ　ａｓ　ｃｏｎｓｉｄｅｒ

覺得
1） more use to express to your phisycal feeling , happyness,
2) give your own opinnion toward sth, could be kind of suggestion

認為
1) also give one's own opinnion toward wth, could be kind of suggestion

some they are exactely the same usage in some point, there is no different meaning.

but 覺得 just got more usage than 認為

When you talk about a feeling, you can but use 觉得. Cherry's first reply is good.
But when you talk about some thinking, they are exchangeable.觉得 is an Euphemistic Expression than 认为。Just like:
:What's your name?
:May I have youre name?

觉得是汉语的口语~~~很少用于书面~~

I agree with the first guy. BTW,"认为“ is used more in written english, "觉得" is used more in speaking.

1.in terms of meaning.
1）认为&觉得 both express judgement of something or someone,and sometimes they can replace with each other.
认为 emphasize particularly on showing the opinion after reflect and consideration,the opinion is often based on analyse,comprehension and cognition,so the tone for 认为 is definite ,
While the tone for 觉得 is not very definite, as 觉得 is just by right of individual feeling.

2）And another meaning of 觉得 is "come into being some feeling"，whereas 认为 doesn't have..
e.g.我觉得累。
e.g.我觉得很忙。
e.g.我觉得很伤心。
e.g.我觉得特别难受。

2.in terms of grammar 认为 can be often used in "被--字句"（passive voice）, 觉得 is rarely used in"被--字句"(passive voice).
e.g.他被老师们认为是班上最听话的学生。
e.g.这个电视剧一致被认为是近年来的经典之作。

两个词都是评自己的分析和感觉作出的推论。

觉得：表示说出来的话，不是很明确，揣测出来的可能。模棱两可的表达。

认为：通过对现象的分析得出的更偏向于确认的推论。表示说话人有信心，很自信和确认的方式。
这么说吧，对于回答一个问题，从不确定到很确定的回答，依次如下：
我猜-我想-我觉得-我认为-我确信