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 Casio EX-100 and Panasonic GH4 side-by-side from the front, back and top in their relative dimensions. Casio EX-100 has external dimensions of 119x67x50 mm and weighs 389 g (including batteries). Panasonic GH4 has external dimensions of 133 x 93 x 84 mm (5.24 x 3.66 x 3.31″) and weighs 560 g (1.23 lb / 19.75 oz) (including batteries).
Below you can see the front-view size comparison of the Casio EX-100 and the Panasonic GH4. Casio EX-100 is clearly the smaller of the two cameras. Its body is 14mm narrower, 26mm shorter and 34mm thinner than Panasonic GH4. As you can tell, actually this is not a fair size comparison since Casio EX-100 has a built-in lens but Panasonic GH4 doesn't. Once you put a lens on GH4, its thickness will increase significantly.
Here is the back view size comparison of the Casio EX-100 and Panasonic GH4.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Casio EX-100 is significantly lighter (171g ) than the Panasonic GH4 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 GH4, the total kit will weigh much higher.
Weather Sealing
Thanks to the weather-sealed body of the GH4, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to the EX-100.
LCD Screen Size and Features
Casio EX-100's 3.50" LCD screen is slightly larger than Panasonic GH4's 3" screen.