二者的区别
at the end of意为“在……结束时、在……的'尽头”，可用以指时间或处所，强调一段时间的结束点或某段路程的终止处，例如：
Our school held a sports meeting at the end of last year.去年年终我校举行了一次运动会。
At the end of this street you’ll find a bookshop.在这条街的尽头你可瞧见一家书店。
In the end意为“最终、最后”与at last 或者finally同义。例如：
In the end they caught the thief.
in the end例句：
1、In the end it was his stomach and lungs that packed up
最后，他的胃和肺衰竭了。
2、In the end you have to readjust your expectations
最后，你需要调整你的预期。
3、In the end, she sort of pushed it
最后，她几乎是用了推的。
at the end例句
1、He parted with us at the end of the trip.
旅行结束时他和我们分手了。
2、This point is developed further at the end of this chapter
这一点在本章结尾处有进一步阐释。
3、He's at the end of his tether.
他没着儿了。