Simplify the following text for a Grade 12 native English-speaking person.
Original: Vladimir Propp , in his Morphology of the Folktale , criticized the common distinction between `` fairy tales '' and `` animal tales '' on the grounds that many tales contained both fantastic elements and animals .
Simplified: Vladimir Propp criticized the difference between `` fairy tales '' and `` animal tales '' in his book Morphology of the Folktale .