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 VG-110 and Nikon D90 side-by-side from the front, back and top in their relative dimensions. Olympus VG-110 has external dimensions of 92 x 54 x 20 mm (3.62 x 2.13 x 0.79″) and weighs 105 g (0.23 lb / 3.70 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 Olympus VG-110 and the Nikon D90. Olympus VG-110 is clearly the smaller of the two cameras. Its body is 40mm narrower, 49mm shorter and 57mm thinner than Nikon D90. As you can tell, actually this is not a fair size comparison since Olympus VG-110 has a built-in lens but Nikon D90 doesn't. Once you put a lens on D90, its thickness will increase significantly.
Now lets look at the top view comparison of Olympus VG-110 and Nikon D90.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Olympus VG-110 is significantly lighter (598g ) 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 Olympus VG-110 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 Olympus VG-110's 2.7" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.