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 Nikon D3100 and Panasonic TS3 side-by-side from the front, back and top in their relative dimensions. Nikon D3100 has external dimensions of 124 x 96 x 75 mm (4.88 x 3.78 x 2.95″) and weighs 505 g (1.11 lb / 17.81 oz) (including batteries). Panasonic TS3 has external dimensions of 103 x 64 x 27 mm (4.06 x 2.52 x 1.06″) and weighs 197 g (0.43 lb / 6.95 oz) (including batteries).
Below you can see the front-view size comparison of the Nikon D3100 and the Panasonic TS3. Panasonic TS3 is clearly the smaller of the two cameras. Its body is 21mm narrower, 32mm shorter and 48mm thinner than Nikon D3100. As you can tell, actually this is not a fair size comparison since Panasonic TS3 has a built-in lens but Nikon D3100 doesn't. Once you put a lens on D3100, its thickness will increase significantly.
Here is the back view size comparison of the Nikon D3100 and Panasonic TS3.
Now lets look at the top view comparison of Nikon D3100 and Panasonic TS3.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Panasonic TS3 is significantly lighter (308g ) than the Nikon D3100 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 D3100, the total kit will weigh much higher.
Weather Sealing
Thanks to the weather-sealed body of the TS3, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to the D3100.
LCD Screen Size and Features
Nikon D3100's 3.00" LCD screen is slightly larger than Panasonic TS3's 2.7" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.