Fantasy and Fantastic, two distinct genres !
As a general rule, it is difficult to establish with clarity the difference between these two genres of the imaginary world. But we will try our luck !
First of all, we can perceive Fantasy as the literature of the wonderful.
Where the supernatural is an integral part of the world, of the laws, of the universe. Thus his appearance does not call into question anything in the plot for the character and the reader.
While for the Fantastic, a supernatural appearance is shocking, disturbing, defies all logic of the plot. There is this famous break with the laws of reality and this break is seen as abnormal for the character and the reader.
Because the supernatural event will create a heavy, frightening atmosphere. The supernatural is sometimes brought in a subtle way whether by the lexical field, or the incarnations, leading the reader to wonder if the supernatural is present or if he should question its reading !