in the end,at the end of ,by the end of的区别 说主要的,

in the end =at last = finally, 表时间, "最后"
at the end of the road, 表地点, "在路的尽头"
at the end of the class, at the end of the day, 表时间, "在要下课的时候", "在一天要结束的时候"
by the end of next week, 表时间, 后跟将来时间, 用将来时态.
we will finish the project by the end of next week. 我们将在下周末完成这个方案.
by the end of last year , 表时间, 后跟过去时间, 用过去完成时态.
We had learnt 20 English songs by the end of last year. 到去年底为止, 我们已经学了20首英文歌.

by the end of和at the end of 都可用来表示时间,但其起止的时间界限有所不同.at the end of 意为“在……末”,指“年、月、日、世纪”等时间点,如：
at the end of this month
（在本月底）
by the end of 意为“不迟于”,强调“最后时限”,其中by＝not later than,概括了before和at两者的意思,如：
by the end of this month
（直至本月底为止）
in the end就是在最后
这个不用解释了吧