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 Pentax K-500 and Samsung ST600 side-by-side from the front, back and top in their relative dimensions. Pentax K-500 has external dimensions of 130 x 97 x 71 mm (5.12 x 3.82 x 2.8″) and weighs 646 g (1.42 lb / 22.79 oz) (including batteries). Samsung ST600 has external dimensions of 104 x 60 x 20 mm (4.09 x 2.36 x 0.79″) and weighs 150 g (0.33 lb / 5.29 oz) (including batteries).
Below you can see the front-view size comparison of the Pentax K-500 and the Samsung ST600. Samsung ST600 is clearly the smaller of the two cameras. Its body is 26mm narrower, 37mm shorter and 51mm thinner than Pentax K-500. As you can tell, actually this is not a fair size comparison since Samsung ST600 has a built-in lens but Pentax K-500 doesn't. Once you put a lens on K-500, its thickness will increase significantly.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Samsung ST600 is significantly lighter (496g ) than the Pentax K-500 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 K-500, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Pentax K-500 nor Samsung ST600 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 DSLR Cameras with Weather Sealing Top Compact Cameras with Weather Sealing
LCD Screen Size and Features
Samsung ST600's 3.50" LCD screen is slightly larger than Pentax K-500's 3 screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.