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 Olympus SP-620 UZ and Pentax Q-S1 side-by-side from the front, back and top in their relative dimensions. Olympus SP-620 UZ has external dimensions of 110 x 74 x 74 mm (4.33 x 2.91 x 2.91″) and weighs 435 g (including batteries). Pentax Q-S1 has external dimensions of 105 x 58 x 34 mm (4.13 x 2.28 x 1.34″) and weighs 203 g (0.45 lb / 7.16 oz) (including batteries).
Below you can see the front-view size comparison of the Olympus SP-620 UZ and the Pentax Q-S1. Pentax Q-S1 is clearly the smaller of the two cameras. Its body is 5mm narrower, 16mm shorter and 40mm thinner than Olympus SP-620 UZ. As you can tell, actually this is not a fair size comparison since Olympus SP-620 UZ has a built-in lens but Pentax Q-S1 doesn't. Once you put a lens on Q-S1, its thickness will increase significantly.
Here is the back view size comparison of the Olympus SP-620 UZ and Pentax Q-S1.
Now lets look at the top view comparison of Olympus SP-620 UZ and Pentax Q-S1.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Pentax Q-S1 is significantly lighter (232g ) than the Olympus SP-620 UZ 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 Q-S1, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Olympus SP-620 UZ nor Pentax Q-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
Olympus SP-620 UZ and Pentax Q-S1's LCD screens have the same diagonal size of 3.00 inches.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.