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 S5100 and Nikon P7800 side-by-side from the front, back and top in their relative dimensions. Nikon S5100 has external dimensions of 97 x 57 x 22 mm (3.82 x 2.24 x 0.87″) and weighs 132 g (0.29 lb / 4.66 oz) (including batteries). Nikon P7800 has external dimensions of 119 x 78 x 50 mm (4.69 x 3.07 x 1.97″) and weighs 399 g (0.88 lb / 14.07 oz) (including batteries).
Below you can see the front view size comparison of Nikon S5100 and Nikon P7800. Nikon S5100 is clearly the smaller of the two cameras. Its body is 22mm narrower, 21mm shorter and 28mm thinner than Nikon P7800.
Here is the back view size comparison of Nikon S5100 and Nikon P7800.
Now lets look at the top view comparison of Nikon S5100 and Nikon P7800.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Nikon S5100 is significantly lighter (267g ) than the Nikon P7800 which may become a big advantage especially on long walking trips.
Unfortunately neither Nikon Coolpix S5100 nor Nikon Coolpix P7800 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 Compact Cameras with Weather Sealing
LCD Screen Size and Features
Nikon P7800's 3" LCD screen is slightly larger than Nikon S5100's 2.7" screen.
Moreover, Nikon P7800 sports a Fully Articulated screen
which you can change the angle and position of the screen almost freely, making it possible to shoot from waist or over the head levels, and especially very useful for shooting selfies and video. On the other hand, Nikon S5100 has a fixed type screen which provides almost no flexibility in shooting positions compared to P7800.