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 Panasonic TS1 and Olympus E-P1 side-by-side from the front, back and top in their relative dimensions. Panasonic TS1 has external dimensions of 98 x 63 x 23 mm (3.86 x 2.48 x 0.91″) and weighs 189 g (0.42 lb / 6.67 oz) (including batteries). Olympus E-P1 has external dimensions of 121 x 70 x 36 mm (4.76 x 2.76 x 1.42″) and weighs 355 g (0.78 lb / 12.52 oz) (including batteries).
Below you can see the front-view size comparison of the Panasonic TS1 and the Olympus E-P1. Panasonic TS1 is clearly the smaller of the two cameras. Its body is 23mm narrower, 7mm shorter and 13mm thinner than Olympus E-P1. As you can tell, actually this is not a fair size comparison since Panasonic TS1 has a built-in lens but Olympus E-P1 doesn't. Once you put a lens on E-P1, its thickness will increase significantly.
Here is the back view size comparison of the Panasonic TS1 and Olympus E-P1.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Panasonic TS1 is significantly lighter (166g ) than the Olympus E-P1 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-P1, the total kit will weigh much higher.
Weather Sealing
Thanks to the weather-sealed body of the TS1, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to the E-P1.
LCD Screen Size and Features
Olympus E-P1's 3.00" LCD screen is slightly larger than Panasonic TS1's 2.7" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.