I have already gone - I have just returned
We use already to say something has happened before. We usually use it in affirmative sentences or questions:
We can also use already to express surprise:
We can use just to say something has happened shortly before the time of speaking. We usually use it with the present perfect (e.g. I have gone) and in affirmative sentences:
Note: Sometimes, especially in American English, just is used with the past simple (e.g. I did):
Already pode ser entendido como 'já', enquanto just equivale a 'acabei de':
I've already cleaned everything. Eu já limpei tudo.
William has already left. William já foi.
I have just had dinner. Eu acabei de jantar.
She's just called. Ela acabou de ligar.