Agile Vs Waterfall

Respond to the following in a minimum of 175 words:

The waterfall project management model is often used for non-IT projects, while the Agile project management model is often used for IT projects.

Why is this the case?
What differences between IT and non-IT projects make each more appropriate for a different project management model? Are there exceptions?
What drawbacks might occur from using the waterfall model for an IT project and the Agile approach for a non-IT project?