Below you can see the front-view size comparison of the Olympus E-PL7 and Olympus E-PL9. The Olympus E-PL7 is clearly the smaller of the two cameras. Its body is 2mm narrower, 1 mm shorter and 1 mm thinner than the Olympus E-PL9.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.