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 E-510 and Olympus SP-590 UZ side-by-side from the front, back and top in their relative dimensions. Olympus E-510 has external dimensions of 136 x 92 x 68 mm (5.35 x 3.62 x 2.68″) and weighs 490 g (1.08 lb / 17.28 oz) (including batteries). Olympus SP-590 UZ has external dimensions of 116 x 84 x 81 mm (4.57 x 3.31 x 3.19″) and weighs 413 g (0.91 lb / 14.57 oz) (including batteries).
Below you can see the front-view size comparison of the Olympus E-510 and the Olympus SP-590 UZ. Olympus SP-590 UZ is 20mm narrower and 8mm shorter than Olympus E-510 but it is also 13mm thicker. As you can tell, actually this is not a fair size comparison since Olympus SP-590 UZ has a built-in lens but Olympus E-510 doesn't. Once you put a lens on E-510, its thickness will increase significantly.
Here is the back view size comparison of the Olympus E-510 and Olympus SP-590 UZ.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Olympus SP-590 UZ is significantly lighter (77g ) than the Olympus E-510 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 E-510, the total kit will weigh much higher.
Weather Sealing
Thanks to the weather-sealed body of the SP-590 UZ, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to the E-510.
LCD Screen Size and Features
Olympus SP-590 UZ's 2.70" LCD screen is slightly larger than Olympus E-510's 2.5" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.