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-400 and Olympus E-450 side-by-side from the front, back and top in their relative dimensions. Olympus E-400 has external dimensions of 130 x 91 x 53 mm (5.12 x 3.58 x 2.09″) and weighs 435 g (0.96 lb / 15.34 oz) (including batteries). Olympus E-450 has external dimensions of 130 x 91 x 53 mm (5.12 x 3.58 x 2.09″) and weighs 426 g (0.94 lb / 15.03 oz) (including batteries).
Below you can see the front-view size comparison of the Olympus E-400 and the Olympus E-450. In this case, we can see that Olympus E-400 and Olympus E-450 have the exact same height, width and thickness.
Here is the back view size comparison of the Olympus E-400 and Olympus E-450.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Olympus E-450 is 9g lighter than the Olympus E-400 but we don't think this will make a significant difference.
Also keep in mind that body weight is not the only deciding factor when comparing two interchangeable camera bodies, you also have to take into account the lenses that you will be using with these bodies. Since both Olympus E-400 and Olympus E-450 have the same Four Thirds lens mount and Four Thirds sized sensors, lenses will not be a differentiator on total size of the system.
Weather Sealing
Unfortunately neither the Olympus E-400 nor Olympus E-450 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
LCD Screen Size and Features
Olympus E-450's 2.70" LCD screen is slightly larger than Olympus E-400's 2.5" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.