ok let me explain this clearly.
B Science
1st year
8 subjects worth 6 units of credit (think of this as the units in the HSC)
This is because science covers such a diverse area of study that it is impossible to give you the detail of what subjects you do. Most people pick 2 Biology, 2 chemistry, 2 maths and 2 other science subjects, like Geology depends on what area of science you are interested in.
2nd year. (For demonstration, i'll pick microbiology as my major or area of specilisation)
You must do
MICR2201 Microbiology and immunology AND MICR2011 Microbiology 1 AND BIOS2021 genetics OR BIOC2201 Molecular Biology.
plus 5 other science subjects of your choice.
B MedSc
First year
CHEM1011, CHEM1021, BIOS1201, BIOS1101, MATHS1XXX (diffeent levels of maths to choose from), BSSM1110 perspective in medical science, and 2 science electives, like psychology, or more maths, or physics etc.
2nd year
(For simplicity, i wish to major in Microbiology in Med science, so you can compare and contrast the difference between the two degrees)
MICR2201 AND MICR2011 AND BIOS2021 AND BIOC2201
AND BIOC2101 AND one of Anatomy, physiology or histology subject
BSSM2220 Persective in Medical science II.
As you can see, medical science is more structure as it guides you to the most relevant subjects for your major, whereas science is less strict about your electives (more of them).