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 Casio EX-ZS15 and Olympus E-410 side-by-side from the front, back and top in their relative dimensions. Casio EX-ZS15 has external dimensions of 103 x 59 x 20 mm (4.06 x 2.32 x 0.79″) and weighs 154 g (including batteries). Olympus E-410 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).
Below you can see the front-view size comparison of the Casio EX-ZS15 and the Olympus E-410. Casio EX-ZS15 is clearly the smaller of the two cameras. Its body is 27mm narrower, 32mm shorter and 33mm thinner than Olympus E-410. As you can tell, actually this is not a fair size comparison since Casio EX-ZS15 has a built-in lens but Olympus E-410 doesn't. Once you put a lens on E-410, its thickness will increase significantly.
Here is the back view size comparison of the Casio EX-ZS15 and Olympus E-410.
Now lets look at the top view comparison of Casio EX-ZS15 and Olympus E-410.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Casio EX-ZS15 is significantly lighter (281g ) than the Olympus E-410 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-410, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Casio Exilim EX-ZS15 nor Olympus E-410 / EVOLT E-410 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
Olympus E-410's 2.50" LCD screen is slightly larger than Casio EX-ZS15's screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.