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 NEX-5 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 NEX-5 has external dimensions of 111 x 59 x 38 mm (4.37 x 2.32 x 1.5″) and weighs 287 g (0.63 lb / 10.12 oz) (including batteries).
Below you can see the front view size comparison of Panasonic ZS3 and Sony NEX-5. Panasonic ZS3 is 8mm narrower and 5mm thinner than Sony NEX-5 but it is also 1mm taller. As you can tell, actually this is not a fair size comparison since Panasonic ZS3 has a built-in lens but Sony NEX-5 doesn't. Once you put a lens on NEX-5, its thickness will increase significantly.
Here is the back view size comparison of Panasonic ZS3 and Sony NEX-5.
Now lets look at the top view comparison of Panasonic ZS3 and Sony NEX-5.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Panasonic ZS3 is significantly lighter (58g ) than the Sony NEX-5 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 NEX-5, the total kit will weigh much higher.
Unfortunately neither Panasonic Lumix DMC-ZS3 (Lumix DMC-TZ7) nor Sony Alpha NEX-5 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 Top Mirrorless Cameras with Weather Sealing
LCD Screen Size and Features
Panasonic ZS3 and Sony NEX-5's LCD screens has the same diagonal size of 3".
On the other hand, Sony NEX-5 features a Tilting screen
where you can change the angle of the screen to make it easier to shoot from waist or over the head levels whereas the Panasonic ZS3 has a fixed type screen which provides less flexibility in shooting positions compared to NEX-5.