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-PL2 and Panasonic S2 side-by-side from the front, back and top in their relative dimensions. Olympus E-PL2 has external dimensions of 114 x 72 x 42 mm (4.49 x 2.83 x 1.65″) and weighs 362 g (0.80 lb / 12.77 oz) (including batteries). Panasonic S2 has external dimensions of 98 x 57 x 21 mm (3.86 x 2.24 x 0.83″) and weighs 112 g (0.25 lb / 3.95 oz) (including batteries).
Below you can see the front-view size comparison of the Olympus E-PL2 and the Panasonic S2. Panasonic S2 is clearly the smaller of the two cameras. Its body is 16mm narrower, 15mm shorter and 21mm thinner than Olympus E-PL2. As you can tell, actually this is not a fair size comparison since Panasonic S2 has a built-in lens but Olympus E-PL2 doesn't. Once you put a lens on E-PL2, its thickness will increase significantly.
Here is the back view size comparison of the Olympus E-PL2 and Panasonic S2.
Now lets look at the top view comparison of Olympus E-PL2 and Panasonic S2.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Panasonic S2 is significantly lighter (250g ) than the Olympus E-PL2 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-PL2, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Olympus PEN E-PL2 nor Panasonic Lumix DMC-S2 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-PL2's 3.00" LCD screen is slightly larger than Panasonic S2's 2.7" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.