Monstrosity
"Monstrosities" are monsters in the strictest sense — frightening creatures that are not ordinary, not truly natural, and almost never benign. Some are the results of magical experimentation gone awry (such as owlbears), and others are the product of terrible curses (including minotaurs and yuan-ti). They defy categorization, and in some sense serve as a catch-all category for creatures that don’t fit into any other type.[1]
Magical beast
The "beast" creature-type is dropped from third edition in v3.5, with those creatures either being redefined as either an "animal" or "magical beast" through fourth edition. Subsequently, in fifth edition, "magical beast" is then dropped with most of those creatures being termed a monstrosity.
"Magical beasts are similar to beasts but have supernatural or extraordinary abilities. Example: displacer beast"[2]
"Magical beasts are similar to animals but can have Intelligence scores higher than 2. Magical beasts usually have supernatural or extraordinary abilities, but sometimes are merely bizarre in appearance or habits."[3]