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-PL9 and Sony W550 side-by-side from the front, back and top in their relative dimensions. Olympus E-PL9 has external dimensions of 117 x 68 x 39 mm (4.61 x 2.68 x 1.54″) and weighs 380 g (0.84 lb / 13.40 oz) (including batteries). Sony W550 has external dimensions of 94 x 56 x 19 mm (3.7 x 2.2 x 0.75″) and weighs 110 g (0.24 lb / 3.88 oz) (including batteries).
Below you can see the front-view size comparison of the Olympus E-PL9 and the Sony W550. Sony W550 is clearly the smaller of the two cameras. Its body is 23mm narrower, 12mm shorter and 20mm thinner than Olympus E-PL9. As you can tell, actually this is not a fair size comparison since Sony W550 has a built-in lens but Olympus E-PL9 doesn't. Once you put a lens on E-PL9, its thickness will increase significantly.
Here is the back view size comparison of the Olympus E-PL9 and Sony W550.
Now lets look at the top view comparison of Olympus E-PL9 and Sony W550.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Sony W550 is significantly lighter (270g ) than the Olympus E-PL9 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-PL9, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Olympus PEN E-PL9 nor Sony Cyber-shot DSC-W550 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-PL9 and Sony W550's LCD screens have the same diagonal size of 3.00 inches.
On the other hand, Olympus E-PL9 features a
Tilting screen where you can change the angle of the screen to make it easier to shoot from waist or over-the-head levels whereas the Sony W550 has a fixed type screen which provides less flexibility in shooting positions compared to E-PL9.