In the end and Lastly

In the end adverb - As the end result of a succession or process.

Lastly and in the end are semantically related in at last topic. In some cases you can use "Lastly" instead an adverb phrase "In the end".

Lastly adverb - The item at the end.

In the end and lastly are semantically related in at last topic. You can use "In the end" instead the word "Lastly" as an adverb or a conjunction, if it concerns topics such as finally.