I upgraded my Nikon camera from the D50, which is no longer made, to the D90. Improvements
include better, clearer pictures, faster continuous shooting, a better lens with more range, the
ability to take HD video, the ability to save both jpg and raw images at the same time for each
shot, a bigger screen with the ability to preview shots on the screen, a second auto setting with
the flash disabled (something I use a lot), and much more.
You can see that the body for the new camera is about the
same size as the old one, but the lens is bigger and better.
The viewing screen on the back is bigger, has a plastic protector
and can be used for viewing images and video. (The screen on
the older model can only be used to view pictures after they
are taken.)
When I became used to the sharper images from the new
Nikon, the images from my old pocket camera looked blurry.
So I also upgraded my pocket camera from a Sony to a newer
Canon that takes 10 mp pictures.
The new camera also has a bigger and better viewing screen.
And newer cameras almost always have faster start-up times,
faster saving of images to the memory card, and better lenses.
Even though the new camera has a bigger viewing screen,
it is a little smaller and thinner than my old one and fits
better in my pocket.