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-M10 and Panasonic FH1 side-by-side from the front, back and top in their relative dimensions. Olympus E-M10 has external dimensions of 119 x 82 x 46 mm (4.69 x 3.24 x 1.81″) and weighs 396 g (0.87 lb / 13.97 oz) (including batteries). Panasonic FH1 has external dimensions of 98 x 55 x 23 mm (3.86 x 2.17 x 0.91″) and weighs 163 g (0.36 lb / 5.75 oz) (including batteries).
Below you can see the front-view size comparison of the Olympus E-M10 and the Panasonic FH1. Panasonic FH1 is clearly the smaller of the two cameras. Its body is 21mm narrower, 27mm shorter and 23mm thinner than Olympus E-M10. As you can tell, actually this is not a fair size comparison since Panasonic FH1 has a built-in lens but Olympus E-M10 doesn't. Once you put a lens on E-M10, its thickness will increase significantly.
Here is the back view size comparison of the Olympus E-M10 and Panasonic FH1.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Panasonic FH1 is significantly lighter (233g ) than the Olympus E-M10 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-M10, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Olympus OM-D E-M10 nor Panasonic Lumix DMC-FH1 (Lumix DMC-FS10) 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-M10's 3.00" LCD screen is slightly larger than Panasonic FH1's 2.7" screen.
In addition to the size advantage, Olympus E-M10 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 FH1 has a fixed type screen which provides less flexibility in shooting positions compared to E-M10.