Size and weight is a big decision factor when you are trying to find the ideal camera for your needs.
In this section, We are going to illustrate Canon ELPH 150 IS and Canon A3400 IS side-by-side from the front, back and top in their relative dimensions. Canon ELPH 150 IS has external dimensions of 95 x 57 x 24 mm (3.74 x 2.24 x 0.94″) and weighs 142 g (0.31 lb / 5.01 oz) (including batteries). Canon A3400 IS has external dimensions of 94 x 56 x 21 mm (3.7 x 2.2 x 0.83″) and weighs 126 g (0.28 lb / 4.44 oz) (including batteries).
Below you can see the front view size comparison of Canon ELPH 150 IS and Canon A3400 IS. Canon A3400 IS is clearly the smaller of the two cameras. Its body is 1mm narrower, 1mm shorter and 3mm thinner than Canon ELPH 150 IS.
Here is the back view size comparison of Canon ELPH 150 IS and Canon A3400 IS.
Now lets look at the top view comparison of Canon ELPH 150 IS and Canon A3400 IS.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Canon A3400 IS is 16g lighter than the Canon ELPH 150 IS but we don't think this will make a significant difference.
Unfortunately neither Canon PowerShot ELPH 150 IS (IXUS 155) nor Canon PowerShot A3400 IS provides any type of weather sealing in their body, 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
Canon A3400 IS's 3.00" LCD screen is slightly larger than Canon ELPH 150 IS's 2.7" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.