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 5010 and Olympus E-PL1 side-by-side from the front, back and top in their relative dimensions. Olympus 5010 has external dimensions of 95 x 56 x 20 mm (3.74 x 2.2 x 0.79″) and weighs 126 g (0.28 lb / 4.44 oz) (including batteries). Olympus E-PL1 has external dimensions of 115 x 72 x 42 mm (4.53 x 2.83 x 1.65″) and weighs 334 g (0.74 lb / 11.78 oz) (including batteries).
Below you can see the front-view size comparison of the Olympus 5010 and the Olympus E-PL1. Olympus 5010 is clearly the smaller of the two cameras. Its body is 20mm narrower, 16mm shorter and 22mm thinner than Olympus E-PL1. As you can tell, actually this is not a fair size comparison since Olympus 5010 has a built-in lens but Olympus E-PL1 doesn't. Once you put a lens on E-PL1, its thickness will increase significantly.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Olympus 5010 is significantly lighter (208g ) than the Olympus E-PL1 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-PL1, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Olympus Stylus 5010 (mju 5010) nor Olympus PEN E-PL1 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
Olympus 5010 and Olympus E-PL1's LCD screens have the same diagonal size of 2.70 inches.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.