Combined Courses = Double Degrees
This is where you study in two seperate fields (eg Arts and Laws) in order to earn two full degrees, one for both. You may receive two testamurs. They may take up to two years less to complete than if you had studied them consecutively (as double degree programs tend to require less subjects/credit points for the award of a full degree).
Double Major
This occurs when you are studying for a single degree (eg B Science) and would like to undertake Major studies (ie focus your subjects) towards two areas within the same field. In Science this could be in Physics and Chemistry. Both will appear on the testamur as "B Science in Physics and Chemistry". Areas studied must be from within your own faculty (ie Science for the above example). For exeptions (USyd) to this definition see below.
Single Major, Two Minors
If you would like only one major you will generally take two Minors. These don't have to be within the scope of your own faculty, but they don't count for as much as a second Major. An example would be a B Science in Biotechnology with Minors in French and Chemistry. Here the student is majoring in Biotechnology, so "B Science in Biotechnology" will appear on his/her testamur. His two minor studies will also appear, but not as part of the degree. Your studies in the minors will be recorded but not noteworthy to employers (unless you are applying for a job where the minor is relevant, as it shows the employer you have a pre-existing interest in the area).