in the end vs at last

in the end and at last both are adverbs.

Word	Noun	Adjective	Verb	Adverb
in the end	No	No	No	Yes
at last	No	No	No	Yes

As adverbs, in the end and at last are synonyms defined as:

Other synonyms of in the end include at long last, finally, ultimately.

in the end (adverb)	at last (adverb)
as the end result of a succession or process	as the end result of a succession or process
eventually or after a lengthy period of time