Hi AnkitaBaguli,
The differences between a rectangle and a parallelogram are:
1) A rectangle has all the angles of measure 90° which is not same in parallelogram.
2) The diagonals of a rectangle are equal whereas diagonals of a parallelogram are not.
∠A = ∠C ∠E = ∠F = ∠G = ∠H = 90°
∠B = ∠D EG = FH
AC ≠ BD
Cheers!