I'm sure Laura will give you lots of useful info but briefly...

The Diploma in Digital Photography places the emphasis on the more technical aspects of digital camera settings - sensor response, white balance and sharpening etc. It also covers aspects of editing such as levels, curves and sharpening in software.

2 and 3 are the same course - the old Introduction to Digital Imagining for Photographers (which no longer accepts new students) which has now metamorphisised into the Diploma above.

So the other option now is the Foundation in Digital Photography, which is less technical and instead brings in a healthy dose of basic camera technique such as how to use aperture and shutter controls, composition and using focal lengths effectively,

Hope that helps but Laura is always on hand to help students select the right course for them,

Garry