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 Olympus E-PM2 and Panasonic FP3 side-by-side from the front, back and top in their relative dimensions. Olympus E-PM2 has external dimensions of 110 x 64 x 34 mm (4.33 x 2.52 x 1.34″) and weighs 269 g (0.59 lb / 9.49 oz) (including batteries). Panasonic FP3 has external dimensions of 99 x 59 x 19 mm (3.9 x 2.32 x 0.75″) and weighs 155 g (0.34 lb / 5.47 oz) (including batteries).
Below you can see the front-view size comparison of the Olympus E-PM2 and the Panasonic FP3. Panasonic FP3 is clearly the smaller of the two cameras. Its body is 11mm narrower, 5mm shorter and 15mm thinner than Olympus E-PM2. As you can tell, actually this is not a fair size comparison since Panasonic FP3 has a built-in lens but Olympus E-PM2 doesn't. Once you put a lens on E-PM2, its thickness will increase significantly.
Now lets look at the top view comparison of Olympus E-PM2 and Panasonic FP3.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Panasonic FP3 is significantly lighter (114g ) than the Olympus E-PM2 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-PM2, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Olympus PEN E-PM2 nor Panasonic Lumix DMC-FP3 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 Mirrorless Cameras with Weather Sealing Top Compact Cameras with Weather Sealing
LCD Screen Size and Features
Olympus E-PM2 and Panasonic FP3's LCD screens have the same diagonal size of 3.00 inches.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.