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 Sony S2100 and Sony A7S III side-by-side from the front, back and top in their relative dimensions. Sony S2100 has external dimensions of 98 x 61 x 27 mm (3.86 x 2.4 x 1.06″) and weighs 167 g (0.37 lb / 5.89 oz) (including batteries). Sony A7S III has external dimensions of 129 x 97 x 81 mm (5.08 x 3.82 x 3.19″) and weighs 699 g (1.54 lb / 24.66 oz) (including batteries).
Below you can see the front-view size comparison of the Sony S2100 and the Sony A7S III. Sony S2100 is clearly the smaller of the two cameras. Its body is 31mm narrower, 36mm shorter and 54mm thinner than Sony A7S III. As you can tell, actually this is not a fair size comparison since Sony S2100 has a built-in lens but Sony A7S III doesn't. Once you put a lens on A7S III, its thickness will increase significantly.
Here is the back view size comparison of the Sony S2100 and Sony A7S III.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Sony S2100 is significantly lighter (532g ) than the Sony A7S III 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 A7S III, the total kit will weigh much higher.
Weather Sealing
Thanks to the weather-sealed body of the A7S III, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to the S2100.
LCD Screen Size and Features
Sony S2100 and Sony A7S III's LCD screens have the same diagonal size of 3.00 inches.