Size and weight is a big decision factor when you are trying to find the ideal camera for your needs.
In this section, We are going to illustrate Panasonic ZS15 and Panasonic ZS20 side-by-side from the front, back and top in their relative dimensions. Panasonic ZS15 has external dimensions of 105 x 58 x 33 mm (4.13 x 2.28 x 1.3″) and weighs 208 g (0.46 lb / 7.34 oz) (including batteries). Panasonic ZS20 has external dimensions of 105 x 59 x 28 mm (4.13 x 2.32 x 1.1″) and weighs 206 g (0.45 lb / 7.27 oz) (including batteries).
Below you can see the front view size comparison of Panasonic ZS15 and Panasonic ZS20.
Here is the back view size comparison of Panasonic ZS15 and Panasonic ZS20.
Now lets look at the top view comparison of Panasonic ZS15 and Panasonic ZS20.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Panasonic ZS20 is 2g lighter than the Panasonic ZS15 but we don't think this will make a significant difference.
Unfortunately neither Panasonic Lumix DMC-ZS15 (Lumix DMC-TZ25) nor Panasonic Lumix DMC-ZS20 (Lumix DMC-TZ30) provides any type of weather sealing in their body, 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
LCD Screen Size and Features
Panasonic ZS15 and Panasonic ZS20's LCD screens has the same diagonal size of 3".
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.