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 W310 and Canon SD780 IS side-by-side from the front, back and top in their relative dimensions. Sony W310 has external dimensions of 95 x 55 x 19 mm (3.74 x 2.17 x 0.75″) and weighs 137 g (0.30 lb / 4.83 oz) (including batteries). Canon SD780 IS has external dimensions of 87 x 56 x 18 mm (3.43 x 2.2 x 0.71″) and weighs 155 g (0.34 lb / 5.47 oz) (including batteries).
Below you can see the front-view size comparison of the Sony W310 and the Canon SD780 IS. Canon SD780 IS is 8mm narrower and 1mm thinner than Sony W310 but it is also 1mm taller.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Sony W310 is 18g lighter than the Canon SD780 IS but we don't think this will make a significant difference.
Weather Sealing
Unfortunately neither the Sony Cyber-shot DSC-W310 nor Canon PowerShot SD780 IS (Digital IXUS 100 IS) 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
Sony W310's 2.70" LCD screen is slightly larger than Canon SD780 IS's 2.5 screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.