A rhombus a is a quadrilateral with 4 sides equal in length
All squares are rhombuses
Squares are quadrilaterals with 4 sides = in length AND 4 right angles
Some rhombuses are squares (some not though)
because some rhombuses have angles not = to 90 degrees
So, all squares are rhombuses, but not all rhombuses are squares, Athera is correct.