Size and weight is a big decision factor when you are trying to find the ideal camera for your needs.
In this section, We are going to illustrate Nikon D80 and Casio EX-100 side-by-side from the front, back and top in their relative dimensions. Nikon D80 has external dimensions of 132 x 103 x 77 mm (5.2 x 4.06 x 3.03″) and weighs 668 g (1.47 lb / 23.56 oz) (including batteries). Casio EX-100 has external dimensions of 119x67x50 mm and weighs 389 g (including batteries).
Below you can see the front view size comparison of Nikon D80 and Casio EX-100. Casio EX-100 is clearly the smaller of the two cameras. Its body is 13mm narrower, 36mm shorter and 27mm thinner than Nikon D80. As you can tell, actually this is not a fair size comparison since Casio EX-100 has a built-in lens but Nikon D80 doesn't. Once you put a lens on D80, 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.
Casio EX-100 is significantly lighter (279g ) than the Nikon D80 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 D80, the total kit will weigh much higher.
Unfortunately neither Nikon D80 nor Casio Exilim EX-100 provides any type of weather sealing in their body, 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 DSLR Cameras with Weather Sealing Top Compact Cameras with Weather Sealing
LCD Screen Size and Features
Casio EX-100's 3.5" LCD screen is slightly larger than Nikon D80's 2.5" screen.
In addition to the size advantage, Casio EX-100 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, Nikon D80 has a fixed type screen which provides less flexibility in shooting positions compared to EX-100.