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 Olympus E-M10 IV and Nikon P900 side-by-side from the front, back and top in their relative dimensions. Olympus E-M10 IV has external dimensions of 122 x 84 x 49 mm (4.8 x 3.31 x 1.93″) and weighs 383 g (0.84 lb / 13.51 oz) (including batteries). Nikon P900 has external dimensions of 140 x 103 x 137 mm (5.51 x 4.06 x 5.39″) and weighs 899 g (1.98 lb / 31.71 oz) (including batteries).
Below you can see the front view size comparison of Olympus E-M10 IV and Nikon P900. Olympus E-M10 IV is clearly the smaller of the two cameras. Its body is 18mm narrower, 19mm shorter and 88mm thinner than Nikon P900. As you can tell, actually this is not a fair size comparison since Nikon P900 has a built-in lens but Olympus E-M10 IV doesn't. Once you put a lens on E-M10 IV, its thickness will increase significantly.
Here is the back view size comparison of Olympus E-M10 IV and Nikon P900.
Now lets look at the top view comparison of Olympus E-M10 IV and Nikon P900.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Olympus E-M10 IV is significantly lighter (516g ) than the Nikon P900 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 E-M10 IV, the total kit will weigh much higher.
Unfortunately neither Olympus OM-D E-M10 IV nor Nikon Coolpix P900 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 Mirrorless Cameras with Weather Sealing Top Bridge Cameras with Weather Sealing
LCD Screen Size and Features
Olympus E-M10 IV and Nikon P900's LCD screens has the same diagonal size of 3".
Olympus E-M10 IV features a Tilting only screen
which is mostly only good for shooting from waist or over the head levels. On the other hand, Nikon P900 sports a Fully Articulated screen
which is more flexible and useful especially for taking Selfie shots and video.