At the end implies a point in time, or it simply refers to the position of something. It means the time when something ends.
- At the end of his life, he had no regrets.
- We put a period at the end of every sentence.
- I pay my electricity bill at the end of every month.
- We scored a goal at the end of the match.
- In Disney movies, the princess always marries her prince at the end. (Meaning: marriage happens in the final scenes of the movie.)
In the end suggests that something happens after changes or uncertainty. We use in the end to mean a final result or a final resolution of a situation.
- It was a tough game but we won in the end.
- He gave over fifty interviews but got his dream job in the end.
- In the end, parents know best.
- It was a tough match, but we won in the end.
- In Disney movies, the princess always marries her prince in the end. (Meaning: the princess marries her prince after some difficulties and hurdles.