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 Casio EX-ZR15 and Panasonic ZS8 side-by-side from the front, back and top in their relative dimensions. Casio EX-ZR15 has external dimensions of 102 x 59 x 27 mm (4.02 x 2.32 x 1.06″) and weighs 176 g (0.39 lb / 6.21 oz) (including batteries). Panasonic ZS8 has external dimensions of 105 x 58 x 33 mm (4.13 x 2.28 x 1.3″) and weighs 210 g (0.46 lb / 7.41 oz) (including batteries).
Below you can see the front view size comparison of Casio EX-ZR15 and Panasonic ZS8. Casio EX-ZR15 is 3mm narrower and 6mm thinner than Panasonic ZS8 but it is also 1mm taller.
Here is the back view size comparison of Casio EX-ZR15 and Panasonic ZS8.
Now lets look at the top view comparison of Casio EX-ZR15 and Panasonic ZS8.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Casio EX-ZR15 is significantly lighter (34g ) than the Panasonic ZS8 which may become a big advantage especially on long walking trips.
Unfortunately neither Casio Exilim EX-ZR15 nor Panasonic Lumix DMC-ZS8 (Lumix DMC-TZ18) 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
Casio EX-ZR15 and Panasonic ZS8'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.