finally; after much effort; in the end
Used after a long process or hard work to express that something finally happened. Often follows a verb in past tense or a noun indicating a period of struggle.
See also: のちに
After long discussions, we finally reached an agreement.
at the end of; after (a period)
Used with a time expression to indicate the end of that period. Common with words like 来週, 今月, 今年.
After lengthy negotiations, the contract was finalized.
苦労の末に、彼は夢を実現させた。
After much hardship, he finally realized his dream.
I have to submit the report at the end of next week.
At the end of next month, we're moving to a new office.
After agonizing over it many times, he finally decided to study abroad.
結局 simply marks the final outcome of a situation without necessarily implying a long, hard process, whereas 末に stresses the effort or time spent before the result.
後 is a more formal, literary word for 'after/later', while 末に specifically highlights reaching the end of a period or a long process, often with effort.
after a heated discussion; after much debate
From 末 (すえ, 'end') + particle に, literally 'at the end'. The adverbial use developed from the temporal meaning.