Is it ok to say 맨날 instead of 매일??
매낭 is casual among family and friends.
먜일 is the more formal of the two.
Otherwise either one can be used.
Typo 매날 not 매낭
Yes. Both of them have almost the same exact meaning. I think 맨날 is more colloquial while 매일 is used more often in writing.