어제(eo-je, eoje)
Refers to the day before today, i.e., the immediate past day.
When to use
Describing past events, Writing diary entries, Mentioning past dates
The nuance
Use 어제 to indicate the day immediately before today from the present perspective. It cannot be used for future times or including today.
모레(mo-re, more)
Refers to two days after today, i.e., the day after tomorrow, indicating a future time.
When to use
Making future appointments, Planning schedules, Talking about future dates
The nuance
Use 모레 to indicate the day immediately after tomorrow from the present perspective. It cannot be used for past times.