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 P300 and Nikon D4 side-by-side from the front, back and top in their relative dimensions. Nikon P300 has external dimensions of 103 x 58 x 32 mm (4.06 x 2.28 x 1.26″) and weighs 189 g (0.42 lb / 6.67 oz) (including batteries). Nikon D4 has external dimensions of 160 x 157 x 91 mm (6.3 x 6.18 x 3.58″) and weighs 1340 g (2.95 lb / 47.27 oz) (including batteries).
Below you can see the front-view size comparison of the Nikon P300 and the Nikon D4. Nikon P300 is clearly the smaller of the two cameras. Its body is 57mm narrower, 99mm shorter and 59mm thinner than Nikon D4. As you can tell, actually this is not a fair size comparison since Nikon P300 has a built-in lens but Nikon D4 doesn't. Once you put a lens on D4, its thickness will increase significantly.
Here is the back view size comparison of the Nikon P300 and Nikon D4.
Now lets look at the top view comparison of Nikon P300 and Nikon D4.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Nikon P300 is significantly lighter (1151g ) than the Nikon D4 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 D4, the total kit will weigh much higher.
Weather Sealing
Thanks to the weather-sealed body of the D4, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to the P300.
LCD Screen Size and Features
Nikon D4's 3.20" LCD screen is slightly larger than Nikon P300's 3 screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.