Dear Student,
A rhombus is a special square, because just like a square, all the sides of a rhombus are equal,opposite angles are equal and its diagonals bisect each other. But, there are some differences between a square and a rhombus, one of which is that all angles of a square are right angles, whereas the angles of a rhombus are not. Another one is that the diagonals of a square are equal, whereas the diagonals of a rhombus are not equal.
Regards