“认为”的语气比“觉得”强一些， 说“认为”的时候一般表示说话者是比较确信的，是基于一定事实基础的； 而“觉得”表明说话者可能是基于一定的事实基础但不确信，或表示说话者仅仅是出于一种猜测。

Both have the same meaning, while the former is a little bit more formal than the latter, so you may use the former more in written Chinese and the latter more in spoken Chinese.

感觉认为要比觉得理性一点。 感觉在Daily Conversation中会用的多一点。如果在一个很casual的背景下，经常用认为会让别人觉得你sanctimonious假正经或者too much powerful. 但是在辩论的场合或者是书面文书，认为会让人觉得理由充分，底气十足。感觉则让人觉得很不靠谱

认为:to express their views,tone formal;it's equal to "think". 觉得:to express their feelings,tone casual;it's equal to "feel". In general, they are universal, and Chinese take no particular attention to this point.

“觉得”用的多，没什么区别吧~