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 SD940 IS and Nikon S9100 side-by-side from the front, back and top in their relative dimensions. Canon SD940 IS has external dimensions of 89 x 55 x 20 mm (3.5 x 2.17 x 0.79″) and weighs 120 g (0.26 lb / 4.23 oz) (including batteries). Nikon S9100 has external dimensions of 105 x 62 x 35 mm (4.13 x 2.44 x 1.38″) and weighs 214 g (0.47 lb / 7.55 oz) (including batteries).
Below you can see the front-view size comparison of the Canon SD940 IS and the Nikon S9100. Canon SD940 IS is clearly the smaller of the two cameras. Its body is 16mm narrower, 7mm shorter and 15mm thinner than Nikon S9100.
Here is the back view size comparison of the Canon SD940 IS and Nikon S9100.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Canon SD940 IS is significantly lighter (94g ) than the Nikon S9100 which may become a big advantage especially on long walking trips.
Weather Sealing
Unfortunately neither the Canon PowerShot SD940 IS / Digital IXUS 120 IS nor Nikon Coolpix S9100 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
LCD Screen Size and Features
Nikon S9100's 3.00" LCD screen is slightly larger than Canon SD940 IS's 2.7" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.