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 WX1 and Nikon D90 side-by-side from the front, back and top in their relative dimensions. Sony WX1 has external dimensions of 91 x 52 x 20 mm (3.58 x 2.05 x 0.79″) and weighs 149 g (0.33 lb / 5.26 oz) (including batteries). Nikon D90 has external dimensions of 132 x 103 x 77 mm (5.2 x 4.06 x 3.03″) and weighs 703 g (1.55 lb / 24.80 oz) (including batteries).
Below you can see the front-view size comparison of the Sony WX1 and the Nikon D90. Sony WX1 is clearly the smaller of the two cameras. Its body is 41mm narrower, 51mm shorter and 57mm thinner than Nikon D90. As you can tell, actually this is not a fair size comparison since Sony WX1 has a built-in lens but Nikon D90 doesn't. Once you put a lens on D90, its thickness will increase significantly.
Here is the back view size comparison of the Sony WX1 and Nikon D90.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Sony WX1 is significantly lighter (554g ) than the Nikon D90 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 D90, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Sony Cyber-shot DSC-WX1 nor Nikon D90 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 DSLR Cameras with Weather Sealing
LCD Screen Size and Features
Nikon D90's 3.00" LCD screen is slightly larger than Sony WX1's 2.7" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.