economics/business概念不清，思维混乱！！

各位大侠，问一个我一直搞不明白的问题：

business和economics什么关系？（别笑话我哦）

如：I wanna pursue my career in economics/business
再如I wanna go on studying business/economics
还如I've studied economics/business during my university,but I feel I still lack the knowledges of business/economics, that's why I want to apply for your program.

这里面有没有什么逻辑错误啊，他们俩啥关系，有没有概念大小啊？实在实在搞不清楚，我可不想交给学校的东西有逻辑错误或者连概念都搞不清楚，那就惨了。

所以请大家帮帮忙吧。