Difference between 가장 and 제일?
Could someone please tell me when to use 제일 and when to use 가장? What is the difference between them? Thank you in advance!

Question

Answer

There is no practical difference when they are used in the sense of superlative adverb "the most".

Unlike 가장, 제일 is also used as a noun ("the best") and makes adjectives in the form of 제일의, 제일인, etc.
- 한국 제일의 도시 = The best city in Korea.
- 내가 제일(로) 좋아하는 사람 = The one like the best.
- 피곤할 때는 자는 게 제일이다 = When you're tired, the best thing is to sleep.