В чем разница между remain и maintain ?Пожалуйста, приведите примеры.

Remain has to do with yourself.
I remained calm (I stayed calm)
I remain a student. (I am still a student)
I must remain focused. (I must stay focused)

Maintain is when your are affecting something other than yourself. You are helping that thing remain
I maintained my focus (I kept my focus - Focus is its own noun in this sentence, like a thing that I can keep rather than a quality that describes me. I don’t know if that makes sense)
You must maintain your good grades to receive the scholarship (you must continue to keep your good grades...)