Already
Use this to say 'not anymore' or 'no longer'. It indicates a change from a past state.
This is the most common way to say 'not yet'.
A slightly more formal synonym for 'todavía no', also meaning 'not yet'.
Did you already finish the homework?
Yes, I already ate, thank you.
The bus already left the station.
I used to like coffee, but not anymore.
Are you going to the supermarket? Not yet.
'Ya' is the universal word for 'already' and is understood everywhere.
Extremely common. 'Ya' can also be used emphatically to mean 'Enough!' (¡Ya!) or 'Right now!' (¡Hazlo ya!).
The word is the same, but the pronunciation is different. The 'y' sound is pronounced like 'sh', so 'ya' sounds like 'sha'.
Usage is identical to Latin America. 'Ya' is the standard term.
Standard usage, no significant difference for a beginner to be aware of.
Confusing 'ya' with 'ahora'. — 'Ya' means 'already' and refers to a completed or past action. 'Ahora' means 'now' (at this exact moment). For example, 'Ya comí' (I already ate) vs. 'Ahora como' (I am eating now).
Incorrect placement in a sentence. — 'Ya' almost always goes before the main verb. Saying 'Yo comí ya' sounds unnatural. The correct way is 'Yo ya comí'.
Using 'todavía' for 'yet' in questions. — In English, you ask 'Have you eaten yet?'. In Spanish, you use 'ya': '¿Ya comiste?'. Using 'todavía' in a positive question is incorrect. 'Todavía' is for negative statements like 'Todavía no como' (I haven't eaten yet).