Size and weight is a big decision factor when you are trying to find the ideal camera for your needs.
In this section, We are going to illustrate Panasonic FX48 and Olympus E-PL3 side-by-side from the front, back and top in their relative dimensions. Panasonic FX48 has external dimensions of 95 x 53 x 22 mm (3.74 x 2.09 x 0.87″) and weighs 150 g (0.33 lb / 5.29 oz) (including batteries). Olympus E-PL3 has external dimensions of 110 x 64 x 37 mm (4.33 x 2.52 x 1.46″) and weighs 313 g (0.69 lb / 11.04 oz) (including batteries).
Below you can see the front view size comparison of Panasonic FX48 and Olympus E-PL3. Panasonic FX48 is clearly the smaller of the two cameras. Its body is 15mm narrower, 11mm shorter and 15mm thinner than Olympus E-PL3. As you can tell, actually this is not a fair size comparison since Panasonic FX48 has a built-in lens but Olympus E-PL3 doesn't. Once you put a lens on E-PL3, its thickness will increase significantly.
Here is the back view size comparison of Panasonic FX48 and Olympus E-PL3.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Panasonic FX48 is significantly lighter (163g ) than the Olympus E-PL3 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-PL3, the total kit will weigh much higher.
Unfortunately neither Panasonic Lumix DMC-FX48 (Lumix DMC-FX40) nor Olympus PEN E-PL3 provides any type of weather sealing in their body, 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
Olympus E-PL3's 3" LCD screen is slightly larger than Panasonic FX48's 2.5" screen.
In addition to the size advantage, Olympus E-PL3 LCD screen also has a Tilting feature
where you can change the angle of the screen to make it easier to shoot from waist or over the head levels. On the other hand, Panasonic FX48 has a fixed type screen which provides less flexibility in shooting positions compared to E-PL3.