Parecidas pero distintas
Y
Already se usa casi siempre en frases afirmativas.
I've already sent off the report.
Already se usa en preguntas para expresar sorpresa.
Have you finished already?
Yet se usa normalmente en frases negativas e interrogativas.
Have you finished yet? No, I haven't finished yet.
Yet puede usarse en frases afirmativas pero con idea negativa.
I have yet to meet someone who is truly bilingual.
Still normalmente expresa sorpresa.
You're still here! Are you still waiting? We still haven't heard from them!