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 T90 and Pentax Q10 side-by-side from the front, back and top in their relative dimensions. Sony T90 has external dimensions of 94 x 57 x 15 mm (3.7 x 2.24 x 0.59″) and weighs 148 g (0.33 lb / 5.22 oz) (including batteries). Pentax Q10 has external dimensions of 102 x 58 x 34 mm (4.02 x 2.28 x 1.34″) and weighs 200 g (0.44 lb / 7.05 oz) (including batteries).
Below you can see the front-view size comparison of the Sony T90 and the Pentax Q10. Sony T90 is clearly the smaller of the two cameras. Its body is 8mm narrower, 1mm shorter and 19mm thinner than Pentax Q10. As you can tell, actually this is not a fair size comparison since Sony T90 has a built-in lens but Pentax Q10 doesn't. Once you put a lens on Q10, its thickness will increase significantly.
Here is the back view size comparison of the Sony T90 and Pentax Q10.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Sony T90 is significantly lighter (52g ) than the Pentax Q10 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 Q10, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Sony Cyber-shot DSC-T90 nor Pentax Q10 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
Sony T90 and Pentax Q10'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.