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 Pentax VS20 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). Pentax VS20 has external dimensions of 111 x 61 x 38 mm (4.37 x 2.4 x 1.5″) and weighs 235 g (0.52 lb / 8.29 oz) (including batteries).
Below you can see the front view size comparison of Canon ELPH 150 IS and Pentax VS20. Canon ELPH 150 IS is clearly the smaller of the two cameras. Its body is 16mm narrower, 4mm shorter and 14mm thinner than Pentax VS20.
Here is the back view size comparison of Canon ELPH 150 IS and Pentax VS20.
Now lets look at the top view comparison of Canon ELPH 150 IS and Pentax VS20.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Canon ELPH 150 IS is significantly lighter (93g ) than the Pentax VS20 which may become a big advantage especially on long walking trips.
Unfortunately neither Canon PowerShot ELPH 150 IS (IXUS 155) nor Pentax Optio VS20 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
Pentax VS20'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.