While the name doctaroo might imply being from Oz, his/her posts seem to indicate being an American who is applying for US medical schools. But BD is right...the medical degree is an undergraduate degree, both here and in Oz.
I do take exception with calling a Categorical Surgery position as guaranteed...even in the microcosm of SDN, we see residents fired for all sorts of reasons claimed to be less than sleeping with the PD's wife or flashing cell phone photos of a strip club owner's nether regions.
But yes, in a simplistic fashion (sorry, I was tired last night when I wrote the above response):
preliminary is usually 1 year of surgery, after that what you do is up to you
(categorical) surgery is expected to lead to a complete training track after which you will be a surgeon and operate on people and stuff