Thanks Alkim what you said helped me, kindly let me confirm that I got it correctly by commenting on my conclusion- " The (space each type of cell occupies) volume of primitive unit cell and unit cell is the same."
I will also like to the meaning of this:
I read The unit cell is the smallest structure that repeats itself by translation through the crystal.
Some says premitive unit cells contains atoms only at the corners while a unit cell may contain extra atoms in between(like bcc or fcc).
At one place I found this: