Rectangle  Parallelogram 

 
A rectangle is also a quadrilateral  A parallelogram is also a quadrilateral 
Opposite sides of rectangle are parallel to each other  Opposite sides of parallelogram are also parallel to each other 
Opposite angles of rectangle are equal  opposite angles of parallelogram are also equal 
Adjacent angles of rectangle are supplementary  Adjacent angles of parallelogram are also supplementary 
Diagonals of rectangle bisect each other  Diagonals of parallelogram also bisect each other 

Opposite sides of rectangle are of equal length  Opposite sides of parallelogram are also of equal length 
All angles of a Rectangle are also of 90 Degree each i.e. right angled at each vertex  Angles of parallelogram can be of different degree 
Diagonals of Rectangle are of equal length  Diagonals of parallelogram are not of equal length 