Hello Alex! In majority of situations these words are synonyms. Both can be translated as "to finish", "to end", "to terminate", "to conclude", "to end up", "to be over". Examples: - Alex acabou o seu trabalho. [Alex finished his work] - Alex terminou o seu trabalho. [Alex finished his work] - O filme acabou. [The movie it's over] - O filme terminou. [The movie it's over] - A história deles acabou em casamento. [Their history ended up in marriage] - A história deles terminou em casamento. [Their history ended up in marriage] However, there are some situations where ACABAR is more specific and is not interchangeable with TERMINAR: 1) When you want to give the idea of "to destroy". Examples: - Ele acabou com o meu trabalho. [He destroyed my work] - Ela acabou com o meu brinquedo. [She destroyed my toy] 2) When you want to give the idea of "to give a final touch". Examples: - Ele acabou o trabalho que eu comecei. [He gave a final touch on the work I started.] - Ele deu o acabamento na obra. [He gave the final touch on his artistic creation.] NOTE: you can see that say "Ele acabou meu trabalho" and "Ele acabou com meu trabalho" have two totally different meanings 3) When you want to give a idea of "to consume completely". Examples: - Em breve a floresta vai acabar. [Soon the forest will be finished] - O queijo acabou. [The cheese is over] 4) When you want to give an idea of something just hapenned. Examples: - Ele acabou de chegar. [He just arrived] - Ele acabou de terminar o trabalho. [He just finished the work] NOTE: you see that in this context you can even combine ACABAR and FINISH as they are not interchangeable when acabar has this meaning.

Both mean "finish", however "acabar" also means "just" like in "I just saw her" (Eu acabei de ver ela). Examples Eu acabei/terminei meu teste - I finished my test. A aula acaba/termina as 12:00 - The class finishes at 12:00 Eu acabei de vir do hotel - I just came from the hotel. Hope I could be helpful.

There is no difference. They are synonyms.

You can also use a dictionary if you have questions and just after ask. I use a lot of dictionaries, I like this one for Portuguese: https://www.priberam.pt/DLPO/Default.aspx

Terminar - to terminate, to complete, to finish, to give an end to (with sucess). Acabar - to to not leave anything, to finish, just have made something