Size and weight are big decision factors when you are trying to find the ideal camera for your needs.
In this section, we are going to illustrate the Panasonic FX78 and Olympus E-PL6 side-by-side from the front, back and top in their relative dimensions. Panasonic FX78 has external dimensions of 100 x 55 x 21 mm (3.94 x 2.17 x 0.83″) and weighs 142 g (0.31 lb / 5.01 oz) (including batteries). Olympus E-PL6 has external dimensions of 111 x 64 x 38 mm (4.37 x 2.52 x 1.5″) and weighs 325 g (0.72 lb / 11.46 oz) (including batteries).
Below you can see the front-view size comparison of the Panasonic FX78 and the Olympus E-PL6. Panasonic FX78 is clearly the smaller of the two cameras. Its body is 11mm narrower, 9mm shorter and 17mm thinner than Olympus E-PL6. As you can tell, actually this is not a fair size comparison since Panasonic FX78 has a built-in lens but Olympus E-PL6 doesn't. Once you put a lens on E-PL6, its thickness will increase significantly.
Here is the back view size comparison of the Panasonic FX78 and Olympus E-PL6.
Now lets look at the top view comparison of Panasonic FX78 and Olympus E-PL6.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Panasonic FX78 is significantly lighter (183g ) than the Olympus E-PL6 which may become a big advantage especially on long walking trips.
Again, this comparison may not be very useful in real life as we are comparing the weight of a camera with a built-in lens to the body-only weight of an interchangeable lens camera. Once you put a lens on E-PL6, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Panasonic Lumix DMC-FX78 (Lumix DMC-FX77) nor Olympus PEN E-PL6 provides any type of weather sealing in their bodies, so you have to give extra care especially when you are shooting outdoors. If weather sealing is a must-have feature for you, check these sections: Top Compact Cameras with Weather Sealing Top Mirrorless Cameras with Weather Sealing
LCD Screen Size and Features
Panasonic FX78's 3.50" LCD screen is slightly larger than Olympus E-PL6's 3" screen.