A fake is anything that is made with the intention to deceive; to profit by cheating some person into buying something that is not what they think it is.
To not be a 'fake', it should be possible for an average buyers to tell that a piece is not an original.
In Chinese art and handicraft they way of learning and also in competition, it has always been a tradition to learn by copying the master. In such cases there is also a tradition to leave some clue in seal, mark or otherwise in the execution, that would make it possible for the student to tell it is he, and not the master, who have made something.In those cases when something is made in homage of a Master, expert connoisseurs and collectors might prefer the expression 'not real' rather than fake, taking the intention of the maker into consideration. And also considering the mind game between connoisseur and artist, the ability to see how close it is possible to get to an original.