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 ZS3 and Sony S2100 side-by-side from the front, back and top in their relative dimensions. Panasonic ZS3 has external dimensions of 103 x 60 x 33 mm (4.06 x 2.36 x 1.3″) and weighs 229 g (0.50 lb / 8.08 oz) (including batteries). Sony S2100 has external dimensions of 98 x 61 x 27 mm (3.86 x 2.4 x 1.06″) and weighs 167 g (0.37 lb / 5.89 oz) (including batteries).
Below you can see the front view size comparison of Panasonic ZS3 and Sony S2100. Sony S2100 is 5mm narrower and 6mm thinner than Panasonic ZS3 but it is also 1mm taller.
Here is the back view size comparison of Panasonic ZS3 and Sony S2100.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Sony S2100 is significantly lighter (62g ) than the Panasonic ZS3 which may become a big advantage especially on long walking trips.
Unfortunately neither Panasonic Lumix DMC-ZS3 (Lumix DMC-TZ7) nor Sony Cyber-shot DSC-S2100 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 ZS3 and Sony S2100'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.