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 Nikon L31 and Canon 600D side-by-side from the front, back and top in their relative dimensions. Nikon L31 has external dimensions of 96 x 59 x 29 mm (3.78 x 2.32 x 1.14″) and weighs 160 g (0.35 lb / 5.64 oz) (including batteries). Canon 600D has external dimensions of 133 x 100 x 80 mm (5.24 x 3.94 x 3.15″) and weighs 570 g (1.26 lb / 20.11 oz) (including batteries).
Below you can see the front-view size comparison of the Nikon L31 and the Canon 600D. Nikon L31 is clearly the smaller of the two cameras. Its body is 37mm narrower, 41mm shorter and 51mm thinner than Canon 600D. As you can tell, actually this is not a fair size comparison since Nikon L31 has a built-in lens but Canon 600D doesn't. Once you put a lens on 600D, its thickness will increase significantly.
Here is the back view size comparison of the Nikon L31 and Canon 600D.
Now lets look at the top view comparison of Nikon L31 and Canon 600D.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Nikon L31 is significantly lighter (410g ) than the Canon 600D 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 600D, the total kit will weigh much higher.
Unfortunately neither the Nikon Coolpix L31 nor Canon EOS 600D (EOS Rebel T3i / EOS Kiss X5) provides any type of weather sealing in their bodies, 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 DSLR Cameras with Weather Sealing
LCD Screen Size and Features
Canon 600D's 3.00" LCD screen is slightly larger than Nikon L31's 2.7" screen.
Moreover, Canon 600D sports a Fully Articulated screen
which you can change the angle and position of the screen almost freely, making it possible to shoot from waist or over-the-head levels, and especially very useful for shooting selfies and video. On the other hand, Nikon L31 has a fixed type screen which provides almost no flexibility in shooting positions compared to 600D.