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 FujiFilm S2800HD and Nikon 1 S1 side-by-side from the front, back and top in their relative dimensions. FujiFilm S2800HD has external dimensions of 110 x 74 x 82 mm (4.33 x 2.91 x 3.23″) and weighs 437 g (0.96 lb / 15.41 oz) (including batteries). Nikon 1 S1 has external dimensions of 102 x 61 x 30 mm (4.02 x 2.4 x 1.18″) and weighs 197 g (0.43 lb / 6.95 oz) (including batteries).
Below you can see the front view size comparison of FujiFilm S2800HD and Nikon 1 S1. Nikon 1 S1 is clearly the smaller of the two cameras. Its body is 8mm narrower, 13mm shorter and 52mm thinner than FujiFilm S2800HD. As you can tell, actually this is not a fair size comparison since FujiFilm S2800HD has a built-in lens but Nikon 1 S1 doesn't. Once you put a lens on 1 S1, its thickness will increase significantly.
Here is the back view size comparison of FujiFilm S2800HD and Nikon 1 S1.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Nikon 1 S1 is significantly lighter (240g ) than the FujiFilm S2800HD 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 1 S1, the total kit will weigh much higher.
Unfortunately neither FujiFilm FinePix S2800HD (FinePix S2900HD) nor Nikon 1 S1 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 Bridge Cameras with Weather Sealing Top Mirrorless Cameras with Weather Sealing
LCD Screen Size and Features
FujiFilm S2800HD and Nikon 1 S1's LCD screens has the same diagonal size of 3".
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.