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 Canon A1100 IS and Nikon 1 S1 side-by-side from the front, back and top in their relative dimensions. Canon A1100 IS has external dimensions of 95 x 62 x 31 mm (3.74 x 2.44 x 1.22″) and weighs 150 g (0.33 lb / 5.29 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 the Canon A1100 IS and the Nikon 1 S1. Nikon 1 S1 is 1mm shorter and 1mm thinner than Canon A1100 IS but it is also 7mm wider. As you can tell, actually this is not a fair size comparison since Canon A1100 IS 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 the Canon A1100 IS and Nikon 1 S1.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Canon A1100 IS is significantly lighter (47g ) than the Nikon 1 S1 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.
Weather Sealing
Unfortunately neither the Canon PowerShot A1100 IS nor Nikon 1 S1 provides any type of weather sealing in their bodies, 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 Top Mirrorless Cameras with Weather Sealing
LCD Screen Size and Features
Nikon 1 S1's 3.00" LCD screen is slightly larger than Canon A1100 IS's 2.5" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.