What is the difference between SMALL format SLR camera and Medium format SLR camera?

Please explain me as simply as possible,
I'm reading in the book (have to do an assignment) but I can't understand the point. There's written in most of small format SLR cameras the shutter is in the focal plane inside the camera body.
I have Nikon D70, is it small or medium format camera? Because the shutter is in my nikkor lense, not in camera body

The main difference is the quality of the photos (in resolution and sharpness) and the quality of bokeh, or shallow depth of field.

Most "Large Format" DSLR's are known by 'Full-frame.'

The larger sensor also means that you get wider shots. A 300mm on a full-frame is 300mm. A 300mm on a crop sensor, like your D70, is more like 450mm.

In the days of film cameras, 35 MM units were considered "small format" and the larger SLRs, like the Hasselblad, used larger film, (4 x 6), were considered "large format". Ansel Adams used even larger size film, as large as 8 x 10, to get the amazing detail in his photo prints. Standard digital cameras, like your D70, still use the 35 MM plate size and are considered small format. Large format digital cameras are super expensive and mainly used in professional studios.

First, your shutter IS in the camera body, not your lens. The shutter is the object that blocks light from hitting your digital sensor. It is behind the mirror that you can see in the camera when you remove the lens. I think you might be thinking of the aperture. That is part of the lens.

Medium format is about (not quite, but almost) a 3 inch by 3 inch square, meaning the digital sensor or the film is approximately that size for each frame, whereas in small format the sensor is the size of a 35mm piece of film or smaller. The sensor on your D70 is a little smaller than a frame of 35mm film. It is a small format DSLR.

There are also cameras that use film where each frame is 4" x 5". That is large format film.

In short: It's how big you can reproduce it.

About $10, 000. All kidding aside, no your camera is not medium format. There are major differences and I will point out a few. First, besides the $10k starting price, the sensor size is much larger. Sensor Size Comparison http://en.wikipedia.org/...rSizes.svg. Second, you have more stops. A canon 5d mark ii has about 9 stops while a medium format will have 12-13 stops. Third, they are almost all 16 bit files unlike 35mm dslr's which are 12-14bit (resulting in more colors and smoother gradients). Medium format files are also much easier to touchup for magazines.

As one poster said
Most "Large Format" DSLR's are known by 'Full-frame.'
This is incorrect. That is not large format, it is 35mm or Full frame.