You may be surprised knowing that "in the end" and "at the end" are not synonyms. They have different meaning in a sentence at a time. So let us meet them.
- after effort, finally, after all
- it is used to suggest that something happens after a lot changes and problems
- The hero kills the villain, and in the end, hero meets his love. (finally)
- I had been preparing for the exams, in the end, I passed. (after all)
- last, at the point at which something end
- it simply suggest position at the end
- We place full stop at the end of a sentence.
- Company will paid you at the end of week.
Generally, At is used for position: such as at the wall, at the corner, at the door, etc. As at suggests position, at the end means something at the last or final point or position.
However, In means inside of something or into something. So, in the end suggests that something involves inside of something that is its last stage (end).
Books on Grammar: