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 TG-6 and Olympus E-420 side-by-side from the front, back and top in their relative dimensions. Olympus TG-6 has external dimensions of 113 x 66 x 32 mm (4.45 x 2.6 x 1.26″) and weighs 253 g (0.56 lb / 8.92 oz) (including batteries). Olympus E-420 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 TG-6 and the Olympus E-420. Olympus TG-6 is clearly the smaller of the two cameras. Its body is 17mm narrower, 25mm shorter and 21mm thinner than Olympus E-420. As you can tell, actually this is not a fair size comparison since Olympus TG-6 has a built-in lens but Olympus E-420 doesn't. Once you put a lens on E-420, its thickness will increase significantly.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Olympus TG-6 is significantly lighter (173g ) than the Olympus E-420 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-420, the total kit will weigh much higher.
Weather Sealing
Thanks to the weather-sealed body of the TG-6, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to the E-420.
LCD Screen Size and Features
Olympus TG-6's 3.00" LCD screen is slightly larger than Olympus E-420's 2.7" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.