Difference between Rectangle and Rhombus
People often fail to differentiate between rectangle and rhombus, as both of these are quadrilateral shapes. However, the difference between both of these shapes is significant and with a little help, you will be easily able to identify it yourself. Not to mention that both of these shapes are exceptional cases of the parallelograms. The major difference between rectangle and rhombus is that, the opposite sides of the rectangle are equal. In contrast, a rhombus is a shape having four equal sides but in a diamond shape. All sides of the rectangle are at right angle while this is not the case with rhombus shape.
On the other hand, if you bisect the diagonals of a rectangle, they bisect each other at equal length but the triangles that are formed are called congruent right triangles. In addition, the sections of rectangle’s diagonals that are bisected are also of equal length. In contrast, the triangles formed after bisecting the diagonals of a rhombus are called equilateral triangles. The equilateral triangle is a triangle which has all sides of equal lengths and angles.
Not to mention, there is also considerable difference in the internal angles of bisected diagonals. The internal angles of a rhombus are intersected through the diagonals. Similarly, the bisected diagonals of a rectangle produce four internal angles at the right angles.
We can also find considerable difference between these two by moving towards the sides of these shapes. All four sides of the rhombus are equal in length and angle. Using the parallelogram law, we can find out that the sum of square of the diagonals of a rhombus is equal to the fourtime square of its side. Similarly, if we take square of the adjacent sides of a rectangle and sum it up, it will be equal to the square of the diagonals of the rectangle.
Instructions

1
Rectangle:
Having different adjacent sides but equal opposite, all four sides of the rectangle are at the angle of 90 degrees to each other. As the sides are equal, therefore the diagonals of the rectangle are also equal in length. In order to find the area of a rectangle, the individual has to multiple its length by the size of its width.
Image Courtesy: gettyimages.com 
2
Rhombus:
Rhombus is a diamond shape parallelogram, which has all four sides of equal length, is considered similar to the shape of a square. Finding the area of a rhombus is same as a parallelogram.
Image Courtesy: gettyimages.com